What is the simplified form of ( (x+4)(x-9)-x^2 )?
Answer and explanation
Correct answer: -5x-36
First expand the product: \((x+4)(x-9)=x^2-9x+4x-36=x^2-5x-36\). Subtracting \(x^2\) gives \(x^2-x^2-5x-36=-5x-36\). Therefore, option B is correct. In option A, the sign of the \(x\)-term is incorrect. Exam tip: while multiplying binomials, check the signs of the middle terms carefully.
Frequently asked questions
What is the correct answer to this question?
-5x-36
Why is this the correct answer?
First expand the product: \((x+4)(x-9)=x^2-9x+4x-36=x^2-5x-36\). Subtracting \(x^2\) gives \(x^2-x^2-5x-36=-5x-36\). Therefore, option B is correct. In option A, the sign of the \(x\)-term is incorrect. Exam tip: while multiplying binomials, check the signs of the middle terms carefully.
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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