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Using identity, what is the value of \( 997^2 \)?
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Answer and explanation
Correct answer: 994009
Write \(997=1000-3\). Using \((a-b)^2=a^2-2ab+b^2\), \((1000-3)^2=1000^2-2\times1000\times3+3^2=1000000-6000+9=994009\). Therefore, option A is correct. \(9940090\) has an extra zero. Exam tip: for squares of numbers close to 1000, use \((a-b)^2\).
Frequently asked questions
What is the correct answer to this question?
994009
Why is this the correct answer?
Write \(997=1000-3\). Using \((a-b)^2=a^2-2ab+b^2\), \((1000-3)^2=1000^2-2\times1000\times3+3^2=1000000-6000+9=994009\). Therefore, option A is correct. \(9940090\) has an extra zero. Exam tip: for squares of numbers close to 1000, use \((a-b)^2\).
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Exploring Algebraic Identities. Topic: Algebraic identities.
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