What is the value of (15^2-12^2)?
Answer and explanation
Correct answer: 81
Evaluate the squares: \(15^2=225\) and \(12^2=144\). Therefore, \(15^2-12^2=225-144=81\). The result can also be checked using the difference-of-squares identity \(a^2-b^2=(a-b)(a+b)\): \((15-12)(15+12)=3\times27=81\). Exam tip: use the difference-of-squares identity to calculate such expressions quickly and reduce arithmetic errors.
Frequently asked questions
What is the correct answer to this question?
81
Why is this the correct answer?
Evaluate the squares: \(15^2=225\) and \(12^2=144\). Therefore, \(15^2-12^2=225-144=81\). The result can also be checked using the difference-of-squares identity \(a^2-b^2=(a-b)(a+b)\): \((15-12)(15+12)=3\times27=81\). Exam tip: use the difference-of-squares identity to calculate such expressions quickly and reduce arithmetic errors.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems. Topic: Exponents.
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