A rectangle model shows (2x^2+9x+10). Which sides are correct?
Answer and explanation
Correct answer: \((2x+5),\ (x+2)\)
The area of a rectangle is the product of its side lengths. \((2x+5)(x+2)=2x^2+4x+5x+10=2x^2+9x+10\), so the correct sides are \((2x+5)\) and \((x+2)\). In option D, \((2x+10)(x+1)=2x^2+12x+10\), whose middle term is not \(9x\). Exam tip: to check factors, add the two cross-product \(x\)-terms.
Frequently asked questions
What is the correct answer to this question?
\((2x+5),\ (x+2)\)
Why is this the correct answer?
The area of a rectangle is the product of its side lengths. \((2x+5)(x+2)=2x^2+4x+5x+10=2x^2+9x+10\), so the correct sides are \((2x+5)\) and \((x+2)\). In option D, \((2x+10)(x+1)=2x^2+12x+10\), whose middle term is not \(9x\). Exam tip: to check factors, add the two cross-product \(x\)-terms.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Exploring Algebraic Identities. Topic: Visual models of identities.
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