Find the value of \((17^2 - 8^2)\).
Answer and explanation
Correct answer: 225
Reason: Use the difference of squares identity \(a^2 - b^2 = (a-b)(a+b)\). With \(a=17\) and \(b=8\), \((17^2 - 8^2) = (17-8)(17+8) = 9\times25 = 225\). Brief notes on wrong options: option A (81) results from the mistake of computing \((17-8)^2\); option B (353) is the sum \(17^2+8^2\); option D (233) is a likely arithmetic subtraction error. Exam tip: Recognise and apply the identity \(a^2-b^2=(a-b)(a+b)\) to simplify such problems quickly and avoid careless subtraction mistakes.
Frequently asked questions
What is the correct answer to this question?
225
Why is this the correct answer?
Reason: Use the difference of squares identity \(a^2 - b^2 = (a-b)(a+b)\). With \(a=17\) and \(b=8\), \((17^2 - 8^2) = (17-8)(17+8) = 9\times25 = 225\). Brief notes on wrong options: option A (81) results from the mistake of computing \((17-8)^2\); option B (353) is the sum \(17^2+8^2\); option D (233) is a likely arithmetic subtraction error. Exam tip: Recognise and apply the identity \(a^2-b^2=(a-b)(a+b)\) to simplify such problems quickly and avoid careless subtraction mistakes.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems. Topic: Exponents.
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