The coefficient of (n) is (-5), so it is the common difference. In exams, first check the coefficient of (n) in a linear term.
Step 2
Why this answer is correct
The correct answer is A. (-5). The coefficient of (n) is (-5), so it is the common difference. In exams, first check the coefficient of (n) in a linear term.
Step 3
Exam Tip
(n) का गुणांक (-5) है, इसलिए वही सामान्य अंतर है। परीक्षा में रैखिक पद में (n) का गुणांक तुरंत देखें।
D. नहीं, अंतर \(7,19,37,\ldots\) हैं/No, the differences are \(7,19,37,\ldots\)
Step 1
Concept
The consecutive differences are not equal, so it is not an AP. In exams, test constancy of differences, not just the visible pattern.
Step 2
Why this answer is correct
The correct answer is D. नहीं, अंतर \(7,19,37,\ldots\) हैं / No, the differences are \(7,19,37,\ldots\). The consecutive differences are not equal, so it is not an AP. In exams, test constancy of differences, not just the visible pattern.
Step 3
Exam Tip
लगातार अंतर बराबर नहीं हैं, इसलिए यह समांतर श्रेणी नहीं है। परीक्षा में नाम या पैटर्न नहीं, अंतर की स्थिरता जांचें।
Equal differences give (-3t+9=-2t+11), so (t=-2) and (d=15). In exams, subtract first from second and second from third.
Step 2
Why this answer is correct
The correct answer is C. (t=-2,d=15). Equal differences give (-3t+9=-2t+11), so (t=-2) and (d=15). In exams, subtract first from second and second from third.
Step 3
Exam Tip
बराबर अंतर से (-3t+9=-2t+11), इसलिए (t=-2) और (d=15)। परीक्षा में दूसरे से पहला और तीसरे से दूसरा पद घटाएं।
The middle term is the average of the extremes, so \(z=\frac{-17+23}{2}=3\) and (d=20). In exams, handle signs carefully when averaging negatives.
Step 2
Why this answer is correct
The correct answer is D. (z=3,d=20). The middle term is the average of the extremes, so \(z=\frac{-17+23}{2}=3\) and (d=20). In exams, handle signs carefully when averaging negatives.
Step 3
Exam Tip
मध्य पद सिरों का औसत है, इसलिए \(z=\frac{-17+23}{2}=3\) और (d=20)। परीक्षा में ऋणात्मक संख्या जोड़ते समय चिन्ह सावधानी से रखें।
The difference depends on (n), so it is not constant for all (n). In exams, if (n) remains in the difference, it is not an AP.
Step 2
Why this answer is correct
The correct answer is D. कभी नहीं / Never. The difference depends on (n), so it is not constant for all (n). In exams, if (n) remains in the difference, it is not an AP.
Step 3
Exam Tip
अंतर (n) पर निर्भर है, इसलिए सभी (n) के लिए स्थिर नहीं है। परीक्षा में अंतर में (n) बच जाए तो समांतर श्रेणी नहीं मानी जाती।
Equating differences gives (x+5=3x-8), so \(x=\frac{13}{2}\) and \(d=\frac{23}{2}\). In exams, do not reject a fractional answer too quickly.
Step 2
Why this answer is correct
The correct answer is A. \(x=\frac{13}{2},d=\frac{23}{2}\). Equating differences gives (x+5=3x-8), so \(x=\frac{13}{2}\) and \(d=\frac{23}{2}\). In exams, do not reject a fractional answer too quickly.
Step 3
Exam Tip
अंतर बराबर करने पर (x+5=3x-8), इसलिए \(x=\frac{13}{2}\) और \(d=\frac{23}{2}\)। परीक्षा में भिन्न उत्तर से घबराएं नहीं।
In that option, each step increases by (0.75). In exams, use consecutive difference as the test even with decimals.
Step 2
Why this answer is correct
The correct answer is D. (2.5,3.25,4,4.75). In that option, each step increases by (0.75). In exams, use consecutive difference as the test even with decimals.
Step 3
Exam Tip
विकल्प में हर बार (0.75) की वृद्धि है। परीक्षा में दशमलवों में भी लगातार अंतर को ही कसौटी बनाएं।
Each step decreases by \(3.5^\circ\), so \(d=-3.5^\circ\). In exams, use a negative sign for a decreasing sequence.
Step 2
Why this answer is correct
The correct answer is C. \(-3.5^\circ\). Each step decreases by \(3.5^\circ\), so \(d=-3.5^\circ\). In exams, use a negative sign for a decreasing sequence.
Step 3
Exam Tip
हर बार \(3.5^\circ\) की कमी है, इसलिए \(d=-3.5^\circ\)। परीक्षा में घटते अनुक्रम में ऋणात्मक चिन्ह लगाएं।
A. समांतर श्रेणी है और \(d=\sqrt{3}\)/It is an AP and \(d=\sqrt{3}\)
Step 1
Concept
The terms become \(\sqrt{3},2\sqrt{3},3\sqrt{3},4\sqrt{3}\). In exams, simplify radicals before finding differences.
Step 2
Why this answer is correct
The correct answer is A. समांतर श्रेणी है और \(d=\sqrt{3}\) / It is an AP and \(d=\sqrt{3}\). The terms become \(\sqrt{3},2\sqrt{3},3\sqrt{3},4\sqrt{3}\). In exams, simplify radicals before finding differences.
Step 3
Exam Tip
पद \(\sqrt{3},2\sqrt{3},3\sqrt{3},4\sqrt{3}\) बनते हैं। परीक्षा में मूलों को सरल करके ही अंतर निकालें।
In an AP, consecutive differences are equal, so (b-a=c-b). In exams, the same condition can be written as (2b=a+c).
Step 2
Why this answer is correct
The correct answer is D. (b-a=c-b). In an AP, consecutive differences are equal, so (b-a=c-b). In exams, the same condition can be written as (2b=a+c).
Step 3
Exam Tip
समांतर श्रेणी में लगातार अंतर बराबर होते हैं, इसलिए (b-a=c-b)। परीक्षा में इसी को (2b=a+c) भी लिखा जा सकता है।
Multiplying by \(\frac{1}{3}\) changes the difference from (-9) to (-3), and adding (5) does not change it. In exams, separate the effects of addition and multiplication.
Step 2
Why this answer is correct
The correct answer is C. (-3). Multiplying by \(\frac{1}{3}\) changes the difference from (-9) to (-3), and adding (5) does not change it. In exams, separate the effects of addition and multiplication.
Step 3
Exam Tip
\(\frac{1}{3}\) से गुणा करने पर अंतर (-9) से (-3) हो जाता है, और (5) जोड़ने से अंतर नहीं बदलता। परीक्षा में जोड़ और गुणन के प्रभाव अलग करें।
The new sequence jumps three original terms each time, so its difference is (3d=12). In exams, count the gap between selected term numbers.
Step 2
Why this answer is correct
The correct answer is C. (12). The new sequence jumps three original terms each time, so its difference is (3d=12). In exams, count the gap between selected term numbers.
Step 3
Exam Tip
नए अनुक्रम में हर बार तीन पदों की छलांग है, इसलिए अंतर (3d=12) है। परीक्षा में चुने गए पदों के बीच की दूरी गिनें।
The condition \(2r^2=r+r^3\) gives (r(r-1)2=0), so the nonzero value is (1). In exams, always apply the nonzero condition.
Step 2
Why this answer is correct
The correct answer is A. (1). The condition \(2r^2=r+r^3\) gives (r(r-1)2=0), so the nonzero value is (1). In exams, always apply the nonzero condition.
Step 3
Exam Tip
शर्त \(2r^2=r+r^3\) से (r(r-1)2=0) मिलता है, इसलिए शून्येतर मान (1) है। परीक्षा में दी गई शून्येतर शर्त जरूर लगाएं।
For three AP terms, \(2\beta=\alpha+\gamma\), so \(\beta=7\). In exams, treat the middle term as the average of the extremes.
Step 2
Why this answer is correct
The correct answer is C. (7). For three AP terms, \(2\beta=\alpha+\gamma\), so \(\beta=7\). In exams, treat the middle term as the average of the extremes.
Step 3
Exam Tip
तीन पदों में \(2\beta=\alpha+\gamma\), इसलिए \(\beta=7\)। परीक्षा में मध्य पद को सिरों का औसत मानें।
(a_n=(m+1)n), so the coefficient of (n) is (m+1). In exams, combine like terms before identifying the linear coefficient.
Step 2
Why this answer is correct
The correct answer is D. (m+1). (a_n=(m+1)n), so the coefficient of (n) is (m+1). In exams, combine like terms before identifying the linear coefficient.
Step 3
Exam Tip
(a_n=(m+1)n) है, इसलिए (n) का गुणांक (m+1) है। परीक्षा में पहले समान पदों को मिलाकर रैखिक रूप बनाएं।
C. समांतर श्रेणी नहीं है क्योंकि अंतर \(2,3,4,5,\ldots\) हैं/It is not an AP because the differences are \(2,3,4,5,\ldots\)
Step 1
Concept
The consecutive differences keep increasing, so they are not constant. In exams, a famous pattern need not be an AP.
Step 2
Why this answer is correct
The correct answer is C. समांतर श्रेणी नहीं है क्योंकि अंतर \(2,3,4,5,\ldots\) हैं / It is not an AP because the differences are \(2,3,4,5,\ldots\). The consecutive differences keep increasing, so they are not constant. In exams, a famous pattern need not be an AP.
Step 3
Exam Tip
लगातार अंतर बढ़ते जा रहे हैं, इसलिए वे स्थिर नहीं हैं। परीक्षा में प्रसिद्ध पैटर्न होने से समांतर श्रेणी होना जरूरी नहीं।
\(\frac{5}{8}-\frac{7}{8}=-\frac{2}{8}=-\frac{1}{4}\). In exams, with equal denominators, subtract numerators directly.
Step 2
Why this answer is correct
The correct answer is B. \(-\frac{1}{4}\). \(\frac{5}{8}-\frac{7}{8}=-\frac{2}{8}=-\frac{1}{4}\). In exams, with equal denominators, subtract numerators directly.
Step 3
Exam Tip
\(\frac{5}{8}-\frac{7}{8}=-\frac{2}{8}=-\frac{1}{4}\)। परीक्षा में समान हर हो तो अंशों का अंतर तुरंत लें।
D. नहीं, कोई वैध (x) नहीं/No, there is no valid (x)
Step 1
Concept
The middle-term condition gives \(x^2-4=x^2\), which is impossible. In exams, also check that denominators are nonzero.
Step 2
Why this answer is correct
The correct answer is D. नहीं, कोई वैध (x) नहीं / No, there is no valid (x). The middle-term condition gives \(x^2-4=x^2\), which is impossible. In exams, also check that denominators are nonzero.
Step 3
Exam Tip
मध्य पद की शर्त से \(x^2-4=x^2\) मिलता है, जो असंभव है। परीक्षा में हरों के शून्य न होने की शर्त भी देखें।
A. वे समांतर श्रेणी में हैं और (d=3b)/They are in AP and (d=3b)
Step 1
Concept
Both consecutive differences are (3b). In exams, directly find differences in symbolic balanced terms.
Step 2
Why this answer is correct
The correct answer is A. वे समांतर श्रेणी में हैं और (d=3b) / They are in AP and (d=3b). Both consecutive differences are (3b). In exams, directly find differences in symbolic balanced terms.
Step 3
Exam Tip
दोनों लगातार अंतर (3b) हैं। परीक्षा में संतुलित प्रतीकात्मक पदों में अंतर सीधे निकालें।
C. नहीं, अंतर \(4,12,36,\ldots\) हैं/No, the differences are \(4,12,36,\ldots\)
Step 1
Concept
The consecutive differences are not equal, so it is not an AP. In exams, do not confuse a multiplicative pattern with an AP.
Step 2
Why this answer is correct
The correct answer is C. नहीं, अंतर \(4,12,36,\ldots\) हैं / No, the differences are \(4,12,36,\ldots\). The consecutive differences are not equal, so it is not an AP. In exams, do not confuse a multiplicative pattern with an AP.
Step 3
Exam Tip
लगातार अंतर समान नहीं हैं, इसलिए यह समांतर श्रेणी नहीं है। परीक्षा में गुणन पैटर्न को समांतर श्रेणी न मानें।
The common difference is second term minus first term, so (3\lambda+2-\(\lambda-4\)=2\lambda+6). In exams, handle the minus sign before brackets carefully.
Step 2
Why this answer is correct
The correct answer is A. \(2\lambda+6\). The common difference is second term minus first term, so (3\lambda+2-\(\lambda-4\)=2\lambda+6). In exams, handle the minus sign before brackets carefully.
Step 3
Exam Tip
सामान्य अंतर दूसरा पद घटा पहला पद है, इसलिए (3\lambda+2-\(\lambda-4\)=2\lambda+6)। परीक्षा में कोष्ठक हटाते समय ऋण चिन्ह संभालें।
B. नहीं, लगातार अंतर बदलता है/No, the consecutive difference changes
Step 1
Concept
The initial terms are \(1,5,5,9,\ldots\), so the difference is not constant. In exams, test terms containing ((-1)^n) by substituting a few values.
Step 2
Why this answer is correct
The correct answer is B. नहीं, लगातार अंतर बदलता है / No, the consecutive difference changes. The initial terms are \(1,5,5,9,\ldots\), so the difference is not constant. In exams, test terms containing ((-1)^n) by substituting a few values.
Step 3
Exam Tip
प्रारंभिक पद \(1,5,5,9,\ldots\) देते हैं, इसलिए अंतर स्थिर नहीं है। परीक्षा में ((-1)^n) वाले पदों को कुछ मान रखकर जांचें।
The distance increases by (12) kilometres each time. In word problems, still find the same consecutive difference.
Step 2
Why this answer is correct
The correct answer is B. (12) किलोमीटर / (12) kilometres. The distance increases by (12) kilometres each time. In word problems, still find the same consecutive difference.
Step 3
Exam Tip
हर बार दूरी (12) किलोमीटर बढ़ती है। परीक्षा में वास्तविक जीवन प्रश्न में भी वही लगातार अंतर निकालें।
The differences are (k+1,3k-3,3k-3), and equality gives (k=2). In exams, check all consecutive differences for four terms.
Step 2
Why this answer is correct
The correct answer is B. (k=2). The differences are (k+1,3k-3,3k-3), and equality gives (k=2). In exams, check all consecutive differences for four terms.
Step 3
Exam Tip
अंतर (k+1,3k-3,3k-3) हैं और बराबरी से (k=2) मिलता है। परीक्षा में चार पदों में सभी लगातार अंतर जांचें।
Here \(c_n=4\) for every (n), so its common difference is (0). In exams, treat the sequence of differences as a separate sequence.
Step 2
Why this answer is correct
The correct answer is A. (0). Here \(c_n=4\) for every (n), so its common difference is (0). In exams, treat the sequence of differences as a separate sequence.
Step 3
Exam Tip
यहां \(c_n=4\) हर (n) के लिए स्थिर है, इसलिए उसका सामान्य अंतर (0) है। परीक्षा में अंतरों के अनुक्रम को अलग अनुक्रम मानकर देखें।
The middle term is \(m=\frac{14+50}{2}=32\), and (d=18). In exams, the middle term of three AP terms is the average.
Step 2
Why this answer is correct
The correct answer is B. (m=32,d=18). The middle term is \(m=\frac{14+50}{2}=32\), and (d=18). In exams, the middle term of three AP terms is the average.
Step 3
Exam Tip
मध्य पद \(m=\frac{14+50}{2}=32\) है और (d=18)। परीक्षा में तीन पदों में मध्य पद औसत होता है।
C. केवल \(a_2-a_1=a_3-a_2\)/Only \(a_2-a_1=a_3-a_2\)
Step 1
Concept
Checking only the first three terms is not enough for the whole sequence. In exams, the full condition must involve every (n) or all consecutive terms.
Step 2
Why this answer is correct
The correct answer is C. केवल \(a_2-a_1=a_3-a_2\) / Only \(a_2-a_1=a_3-a_2\). Checking only the first three terms is not enough for the whole sequence. In exams, the full condition must involve every (n) or all consecutive terms.
Step 3
Exam Tip
केवल पहले तीन पदों की जांच पूरे अनुक्रम के लिए पर्याप्त नहीं है। परीक्षा में पूरी शर्त में हर (n) या सभी लगातार पद शामिल होने चाहिए।
D. नहीं, लगातार अंतर स्थिर नहीं है/No, the consecutive difference is not constant
Step 1
Concept
The terms are \(\frac{1}{3},\frac{1}{5},\frac{1}{7},\ldots\), and the differences change. In exams, test fractions with changing denominators by differences.
Step 2
Why this answer is correct
The correct answer is D. नहीं, लगातार अंतर स्थिर नहीं है / No, the consecutive difference is not constant. The terms are \(\frac{1}{3},\frac{1}{5},\frac{1}{7},\ldots\), and the differences change. In exams, test fractions with changing denominators by differences.
Step 3
Exam Tip
पद \(\frac{1}{3},\frac{1}{5},\frac{1}{7},\ldots\) देते हैं और अंतर बदलते हैं। परीक्षा में हर बदलने वाले भिन्नों को अंतर से परखें।
The new sequence jumps two original terms each time, so the difference is (2d). In exams, multiply (d) by the term-number jump.
Step 2
Why this answer is correct
The correct answer is B. (2d). The new sequence jumps two original terms each time, so the difference is (2d). In exams, multiply (d) by the term-number jump.
Step 3
Exam Tip
नए अनुक्रम में दो-दो मूल पदों की छलांग है, इसलिए अंतर (2d) है। परीक्षा में पद-संख्या की छलांग को (d) से गुणा करें।
There are (5) intervals between \(a_7\) and \(a_2\), so (5d=35) and (d=7). In exams, subtract term numbers to get intervals.
Step 2
Why this answer is correct
The correct answer is C. (7). There are (5) intervals between \(a_7\) and \(a_2\), so (5d=35) and (d=7). In exams, subtract term numbers to get intervals.
Step 3
Exam Tip
\(a_7\) और \(a_2\) के बीच (5) अंतराल हैं, इसलिए (5d=35) और (d=7)। परीक्षा में पद क्रमांक घटाकर अंतराल पाएं।
B. समांतर श्रेणी है और (d=4)/It is an AP and (d=4)
Step 1
Concept
Each next term adds (4), so the common difference is (4). In exams, a variable constant part does not change the difference.
Step 2
Why this answer is correct
The correct answer is B. समांतर श्रेणी है और (d=4) / It is an AP and (d=4). Each next term adds (4), so the common difference is (4). In exams, a variable constant part does not change the difference.
Step 3
Exam Tip
हर अगले पद में (4) जुड़ता है, इसलिए सामान्य अंतर (4) है। परीक्षा में चर वाला स्थिर भाग अंतर को नहीं बदलता।
C. नहीं, लगातार अंतर स्थिर नहीं है/No, the consecutive difference is not constant
Step 1
Concept
The terms are \(0,0,2,6,\ldots\), and the differences \(0,2,4,\ldots\) change. In exams, expand the product or test initial terms.
Step 2
Why this answer is correct
The correct answer is C. नहीं, लगातार अंतर स्थिर नहीं है / No, the consecutive difference is not constant. The terms are \(0,0,2,6,\ldots\), and the differences \(0,2,4,\ldots\) change. In exams, expand the product or test initial terms.
Step 3
Exam Tip
पद \(0,0,2,6,\ldots\) हैं और अंतर \(0,2,4,\ldots\) बदलते हैं। परीक्षा में गुणन रूप को फैलाकर या पहले पदों से जांचें।
Both consecutive differences are (3a+2b), so the terms are in AP. In exams, also check equality of the two differences.
Step 2
Why this answer is correct
The correct answer is A. (3a+2b). Both consecutive differences are (3a+2b), so the terms are in AP. In exams, also check equality of the two differences.
Step 3
Exam Tip
दोनों लगातार अंतर (3a+2b) हैं, इसलिए ये पद समांतर श्रेणी में हैं। परीक्षा में दोनों अंतरों की समानता भी साथ-साथ जांचें।
Multiplication makes every difference (t) times as large. In exams, apply scaling directly to the common difference.
Step 2
Why this answer is correct
The correct answer is C. (t(b-a)). Multiplication makes every difference (t) times as large. In exams, apply scaling directly to the common difference.
Step 3
Exam Tip
गुणन से हर अंतर (t) गुना हो जाता है। परीक्षा में स्केलिंग सीधे सामान्य अंतर पर भी लागू करें।
Each term is (2.5) less than the previous one, so (d=-2.5). In exams, do not forget the negative sign in decreasing decimal sequences.
Step 2
Why this answer is correct
The correct answer is B. (-2.5). Each term is (2.5) less than the previous one, so (d=-2.5). In exams, do not forget the negative sign in decreasing decimal sequences.
Step 3
Exam Tip
हर पद पिछले से (2.5) कम है, इसलिए (d=-2.5)। परीक्षा में घटते दशमलव अनुक्रम में ऋणात्मक चिन्ह न भूलें।
There are (4) equal gaps between the first and fifth terms, so \(d=\frac{19-3}{4}=4\). In exams, divide the total difference between distant terms by the number of gaps.
Step 2
Why this answer is correct
The correct answer is B. (x=7,y=15,d=4). There are (4) equal gaps between the first and fifth terms, so \(d=\frac{19-3}{4}=4\). In exams, divide the total difference between distant terms by the number of gaps.
Step 3
Exam Tip
पहले और पांचवें पद के बीच (4) बराबर अंतराल हैं, इसलिए \(d=\frac{19-3}{4}=4\)। परीक्षा में दूर दिए गए पदों के बीच कुल अंतर को अंतरालों की संख्या से भाग दें।
