Which of the following expressions can be factorised using the identity for the sum of cubes?
Answer and explanation
Correct answer: \(x^3+27\)
Here \(27=3^3\), so \(x^3+27=x^3+3^3=(x+3)(x^2-3x+9)\), which fits the sum-of-cubes identity. \(x^3-27\) is a difference of cubes. Exam tip: check whether the constant is a perfect cube.
Frequently asked questions
What is the correct answer to this question?
\(x^3+27\)
Why is this the correct answer?
Here \(27=3^3\), so \(x^3+27=x^3+3^3=(x+3)(x^2-3x+9)\), which fits the sum-of-cubes identity. \(x^3-27\) is a difference of cubes. Exam tip: check whether the constant is a perfect cube.
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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