What is the value of \(15^2 - 11^2\)?
Answer and explanation
Correct answer: 104
Use the difference of squares identity: \(a^2-b^2=(a-b)(a+b)\). Here \(15^2-11^2=(15-11)(15+11)=4\times26=104\). The closest distractor 94 is wrong — it would correspond to a subtraction or squaring error (for example misreading 121 as 131). Correct application of the identity gives 104. Exam tip: convert \(a^2-b^2\) to \((a-b)(a+b)\) to simplify mental calculation and avoid large subtractions.
Frequently asked questions
What is the correct answer to this question?
104
Why is this the correct answer?
Use the difference of squares identity: \(a^2-b^2=(a-b)(a+b)\). Here \(15^2-11^2=(15-11)(15+11)=4\times26=104\). The closest distractor 94 is wrong — it would correspond to a subtraction or squaring error (for example misreading 121 as 131). Correct application of the identity gives 104. Exam tip: convert \(a^2-b^2\) to \((a-b)(a+b)\) to simplify mental calculation and avoid large subtractions.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems. Topic: Exponents.
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