What is the value of \((9^3-9^2)\)?
Answer and explanation
Correct answer: 648
Compute the powers first: \(9^3=729\) and \(9^2=81\). So \(9^3-9^2=729-81=648\). Alternate method: factor out \(9^2\): \(9^2(9-1)=81\times8=648\). The closest distractor 658 is a simple arithmetic slip (off by 10); 729 would be the result of forgetting to subtract, and 81 is just \(9^2\). Exam tip: factor the common power \(a^n(a-1)\) or compute powers then subtract to avoid mistakes.
Frequently asked questions
What is the correct answer to this question?
648
Why is this the correct answer?
Compute the powers first: \(9^3=729\) and \(9^2=81\). So \(9^3-9^2=729-81=648\). Alternate method: factor out \(9^2\): \(9^2(9-1)=81\times8=648\). The closest distractor 658 is a simple arithmetic slip (off by 10); 729 would be the result of forgetting to subtract, and 81 is just \(9^2\). Exam tip: factor the common power \(a^n(a-1)\) or compute powers then subtract to avoid 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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