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Using an algebraic identity, find the value of \(98^2\).
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Answer and explanation
Correct answer: 9604
Since \(98=100-2\), use the identity \((a-b)^2=a^2-2ab+b^2\): \(98^2=(100-2)^2=100^2-2(100)(2)+2^2=10000-400+4=9604\). Therefore, option A is correct. Exam tip: For squaring a number close to a convenient base such as 100, use the identity \((a\pm b)^2\).
Frequently asked questions
What is the correct answer to this question?
9604
Why is this the correct answer?
Since \(98=100-2\), use the identity \((a-b)^2=a^2-2ab+b^2\): \(98^2=(100-2)^2=100^2-2(100)(2)+2^2=10000-400+4=9604\). Therefore, option A is correct. Exam tip: For squaring a number close to a convenient base such as 100, use the identity \((a\pm b)^2\).
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Polynomials. Topic: Operations on real numbers and the laws of exponents.
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