This question needs careful substitution after elimination; careless cancellation gives a wrong value. Check each obtained value in both equations before marking.
Step 2
Why this answer is correct
The correct answer is A. (9). This question needs careful substitution after elimination; careless cancellation gives a wrong value. Check each obtained value in both equations before marking.
Step 3
Exam Tip
घटाने पर (8y=24), इसलिए (y=3) और \(x=\frac{19}{5}\) नहीं बल्कि दूसरे में रखने से \(x=\frac{19}{5}\) नहीं आता; सही हल (x=5,y=2) नहीं है, इसलिए सावधानी चाहिए।
B. बिंदु (\left\(4,3\right\))/Point (\left\(4,3\right\))
Step 1
Concept
Substituting (\left\(4,3\right\)) gives (2\left\(4\right\)-3\left\(3\right\)=-1), so it is not correct. The correct solution is (\left\(\frac{22}{5},\frac{13}{5}\right\)).
Step 2
Why this answer is correct
The correct answer is B. बिंदु (\left\(4,3\right\)) / Point (\left\(4,3\right\)). Substituting (\left\(4,3\right\)) gives (2\left\(4\right\)-3\left\(3\right\)=-1), so it is not correct. The correct solution is (\left\(\frac{22}{5},\frac{13}{5}\right\)).
Step 3
Exam Tip
(\left\(4,3\right\)) रखने पर (2\left\(4\right\)-3\left\(3\right\)=-1), इसलिए यह नहीं है। सही हल (\left\(\frac{22}{5},\frac{13}{5}\right\)) है।
The roots are (4) and (5). Direct substitution gives \(\frac{6}{2}+\frac{7}{3}=\frac{16}{3}\), so option (A) should be correct.
Step 2
Why this answer is correct
The correct answer is B. \(\frac{17}{3}\). The roots are (4) and (5). Direct substitution gives \(\frac{6}{2}+\frac{7}{3}=\frac{16}{3}\), so option (A) should be correct.
Step 3
Exam Tip
जड़ें (4) और (5) हैं। सीधे रखने पर \(\frac{6}{2}+\frac{7}{3}=\frac{16}{3}\) मिलता है, इसलिए विकल्प (A) सही होना चाहिए।
For real roots, \(D\ge0\) is required. Here (D=36(a-1)2-36\(a^2-4a-5\)=72a+216), so the exact condition is \(a\ge-3\), not \(a\ge-\frac{7}{2}\).
Step 2
Why this answer is correct
The correct answer is A. \(a\ge-\frac{7}{2}\). For real roots, \(D\ge0\) is required. Here (D=36(a-1)2-36\(a^2-4a-5\)=72a+216), so the exact condition is \(a\ge-3\), not \(a\ge-\frac{7}{2}\).
Step 3
Exam Tip
वास्तविक जड़ों के लिए \(D\ge0\) चाहिए। यहाँ (D=36(a-1)2-36\(a^2-4a-5\)=72a+216), इसलिए \(a\ge-\frac{7}{2}\) नहीं बल्कि \(a\ge-3\) होगा।
The prime pairs with sum (10) are ((3,7)) and ((5,5)). Hence (m=21) or (m=25), and their sum is (46), so option (B) should be correct.
Step 2
Why this answer is correct
The correct answer is A. (42). The prime pairs with sum (10) are ((3,7)) and ((5,5)). Hence (m=21) or (m=25), and their sum is (46), so option (B) should be correct.
Step 3
Exam Tip
योग (10) वाली अभाज्य जोड़ियाँ ((3,7)) और ((5,5)) हैं। इसलिए (m=21) या (m=25), और योग (46) है, अतः विकल्प (B) सही होना चाहिए।
Putting (x=3) gives (9-3(m-2)+m-6=0), so \(m=\frac{9}{2}\). The product is \(-\frac{3}{2}\), so the other root is \(-\frac{1}{2}\); hence no option is correct.
Step 2
Why this answer is correct
The correct answer is A. (1). Putting (x=3) gives (9-3(m-2)+m-6=0), so \(m=\frac{9}{2}\). The product is \(-\frac{3}{2}\), so the other root is \(-\frac{1}{2}\); hence no option is correct.
Step 3
Exam Tip
(x=3) रखने पर (9-3(m-2)+m-6=0), इसलिए \(m=\frac{9}{2}\)। गुणनफल \(m-6=-\frac{3}{2}\) है, अतः दूसरी जड़ \(-\frac{1}{2}\) होगी, इसलिए कोई विकल्प सही नहीं है।
Since \(\alpha^2=3\alpha+1\), the expression becomes (3\alpha+1+3\beta-1=3\(\alpha+\beta\)=9), so no option is correct. The correct value is (9).
Step 2
Why this answer is correct
The correct answer is A. (8). Since \(\alpha^2=3\alpha+1\), the expression becomes (3\alpha+1+3\beta-1=3\(\alpha+\beta\)=9), so no option is correct. The correct value is (9).
Step 3
Exam Tip
क्योंकि \(\alpha^2=3\alpha+1\), व्यंजक (3\alpha+1+3\beta-1=3\(\alpha+\beta\)=9) बनता है, इसलिए कोई विकल्प सही नहीं है। सही मान (9) होगा।
The roots are (3) and (5). Substitution gives \(\frac{5}{1}+\frac{7}{3}=\frac{22}{3}\), so none of the options is correct; the correct value should be \(\frac{22}{3}\).
Step 2
Why this answer is correct
The correct answer is A. (8). The roots are (3) and (5). Substitution gives \(\frac{5}{1}+\frac{7}{3}=\frac{22}{3}\), so none of the options is correct; the correct value should be \(\frac{22}{3}\).
Step 3
Exam Tip
जड़ें (3) और (5) हैं। सीधे रखने पर \(\frac{5}{1}+\frac{7}{3}=\frac{22}{3}\) आता है, इसलिए विकल्पों में कोई सही नहीं; सही प्रश्न के लिए उत्तर \(\frac{22}{3}\) होना चाहिए।
\(x^2=3+2\sqrt{2}\) and \(x^3=7+5\sqrt{2}\), so \(x^3-3x=4+2\sqrt{2}\). The correct value is not in the options so calculate carefully.
Step 2
Why this answer is correct
The correct answer is A. \(2\sqrt{2}\). \(x^2=3+2\sqrt{2}\) and \(x^3=7+5\sqrt{2}\), so \(x^3-3x=4+2\sqrt{2}\). The correct value is not in the options so calculate carefully.
Step 3
Exam Tip
\(x^2=3+2\sqrt{2}\) और \(x^3=7+5\sqrt{2}\), इसलिए \(x^3-3x=4+2\sqrt{2}\) होता है। सही मान विकल्पों में नहीं है इसलिए गणना सावधानी से करें।
\(\frac{1}{2+\sqrt{7}}\) equals \(\frac{2-\sqrt{7}}{-3}=\frac{\sqrt{7}-2}{3}\). So \(x+\frac{1}{x}=2+\sqrt{7}+\frac{\sqrt{7}-2}{3}=\frac{4+4\sqrt{7}}{3}\).
Step 2
Why this answer is correct
The correct answer is A. \(2\sqrt{7}\). \(\frac{1}{2+\sqrt{7}}\) equals \(\frac{2-\sqrt{7}}{-3}=\frac{\sqrt{7}-2}{3}\). So \(x+\frac{1}{x}=2+\sqrt{7}+\frac{\sqrt{7}-2}{3}=\frac{4+4\sqrt{7}}{3}\).
Step 3
Exam Tip
\(\frac{1}{2+\sqrt{7}}=\frac{\sqrt{7}-2}{3}\) नहीं बल्कि हर (4-7=-3) से मान \(\frac{2-\sqrt{7}}{3}\) है इसलिए सीधा विकल्प नहीं बनेगा। सही सरलीकरण जांचे बिना उत्तर न चुनें।
