What is the simplified form of ( (2x-1)(2x+7)-(2x+1)(2x+5) )?
Answer and explanation
Correct answer: \(4x-2\)
\((2x-1)(2x+7)=4x^2+12x-7\), while \((2x+1)(2x+5)=4x^2+8x+5\). Therefore, their difference is \((4x^2+12x-7)-(4x^2+8x+5)=4x-2\). The value \(-12\) results from expanding the middle term of the second product incorrectly. Exam tip: when subtracting an expression in brackets, change the sign of every term in the second bracket before combining like terms.
Frequently asked questions
What is the correct answer to this question?
\(4x-2\)
Why is this the correct answer?
\((2x-1)(2x+7)=4x^2+12x-7\), while \((2x+1)(2x+5)=4x^2+8x+5\). Therefore, their difference is \((4x^2+12x-7)-(4x^2+8x+5)=4x-2\). The value \(-12\) results from expanding the middle term of the second product incorrectly. Exam tip: when subtracting an expression in brackets, change the sign of every term in the second bracket before combining like terms.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Exploring Algebraic Identities. Topic: Algebraic identities.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
