If (5^n=\dfrac{1}{125}), what is the value of (n)?
Since (125=5^3), (\dfrac{1}{125}=5^{-3}), so (n=-3). In exams, connect a reciprocal with a negative exponent.
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SubjectsMathematics
वास्तविक संख्याओं पर संक्रियाएँ और घातांक के नियम
In this Class 10 Mathematics topic from the Polynomials chapter, students strengthen their understanding of operations on real numbers and the laws of exponents. They learn to add, subtract, multiply and divide numerical expressions accurately, use exponent rules for products, quotients and powers, and simplify expressions involving positive, zero and negative exponents where appropriate. The topic builds fluency in working with polynomial terms, comparing equivalent forms, and checking calculations through properties such as commutativity, associativity and distributivity. Examples connect numerical rules with algebraic manipulation and related exercises.
TOPIC PRACTICE
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Since (125=5^3), (\dfrac{1}{125}=5^{-3}), so (n=-3). In exams, connect a reciprocal with a negative exponent.
View question detailsTaking (7^4) common in the numerator gives (\dfrac{7^4(7-1)}{7^4}=6). In exams, taking a common factor makes calculation shorter.
View question detailsThe numerator is (2^{10}+2^{10}=2\times 2^{10}=2^{11}), so (\dfrac{2^{11}}{2^9}=2^2=4). In exams, first combine like terms and then apply exponent laws.
View question detailsUsing the distributive law, (x(x-3)+2(x-3)=x^2-x-6). In exams, check the sign of the middle term carefully.
View question detailsBecause (x^3-8=(x-2)(x^2+2x+4)), the quotient is (x^2+2x+4). In exams, remember the identity for cubes.
View question detailsSubstituting \(x=2\), we get \(P(2)=2^3-4(2)+1=8-8+1=1\). Hence, option A is correct. Option B results from forgetting the final \(+1\). Exam tip: substitute the value carefully and simplify each term, especially the term containing the exponent.
View question details(\sqrt{12}\times \sqrt{27}=\sqrt{324}=18). In exams, use (\sqrt{a}\sqrt{b}=\sqrt{ab}) for non-negative numbers.
View question details(\dfrac{\sqrt{45}}{\sqrt{5}}=\sqrt{\dfrac{45}{5}}=\sqrt{9}=3). In exams, simplify division inside the root first.
View question detailsBecause (\sqrt{a^2}=a) and (\sqrt{b^4}=b^2), the answer is (ab^2). In exams, note the condition that variables are positive.
View question details\(\dfrac{x^2}{y^{-1}}=x^2y\), so the whole square is \(x^4y^2\). In exams, simplify a negative exponent by moving its position.
View question details(a^2b-ab^2=4(-3)-2(9)=-12-18=-30). In exams, the square of a negative number is always positive.
View question details((-2)^4=16) and ((-2)^3=-8), so (16-(-8)=24). In exams, odd and even powers have different signs.
View question detailsA negative exponent inverts the fraction, so \(\left(-\dfrac{1}{2}\right)^{-3}=(-2)^3=-8\). In exams, keep the sign of a negative base according to the power.
View question details((4x^{-2})^{-1}=4^{-1}x^2=\dfrac{x^2}{4}). In exams, apply the outside exponent to every factor of a product.
View question detailsWhen powers with the same base are multiplied, their exponents are added, so \(a^m\cdot a^n=a^{m+n}\). In option B, exponents multiply: \((a^m)^n=a^{mn}\). Exam tip: first check whether the bases are the same before applying an exponent law.
View question detailsWhen the two squares are added, the surd terms cancel and (7+7=14). In exams, irrational terms often cancel in conjugate expressions.
View question detailsBy the power of a power law, ((x^{\frac{1}{3}})^6=x^{\frac{6}{3}}=x^2). In exams, multiply the exponents.
View question detailsIn division, (a^{2-(-1)}=a^3) and (b^{-3-1}=b^{-4}), so the answer is (\dfrac{a^3}{b^4}). In exams, subtract exponents of like variables separately.
View question detailsFirst, \(\left(\dfrac{81}{16}\right)^{\frac{1}{2}}=\dfrac{9}{4}\), then the negative exponent gives (\dfrac{4}{9}). In exams, check both the square root and the reciprocal.
View question details((10^3)^2=10^6) and (\dfrac{10^6}{10^{-2}}=10^{6-(-2)}=10^8). In exams, be careful while subtracting a negative exponent.
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