Which expansion is correct from the visual model of a square with side (2p-7)?
Answer and explanation
Correct answer: \(4p^2-28p+49\)
The area of the square is the square of its side: \((2p-7)^2\). Using \((a-b)^2=a^2-2ab+b^2\), with \(a=2p\) and \(b=7\), gives \(4p^2-28p+49\). In the visual model, two \(2p\times 7\) strips are removed, so the middle term is \(-28p\). Option A has only half of the required middle term. Exam tip: the middle term in \((a-b)^2\) is always negative.
Frequently asked questions
What is the correct answer to this question?
\(4p^2-28p+49\)
Why is this the correct answer?
The area of the square is the square of its side: \((2p-7)^2\). Using \((a-b)^2=a^2-2ab+b^2\), with \(a=2p\) and \(b=7\), gives \(4p^2-28p+49\). In the visual model, two \(2p\times 7\) strips are removed, so the middle term is \(-28p\). Option A has only half of the required middle term. Exam tip: the middle term in \((a-b)^2\) is always negative.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Exploring Algebraic Identities. Topic: Visual models of identities.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
