Question

Factorising the expression $7a^2-14a+7$ results in :

• A. $7(a-2)(a-2)$
• B. $7(a-1)(a+1)$
• C. $7(a-1)(a-1)$
• D. $(a-1)(a-1)$

Answer 1

Answer: (C)

$7(a-1)(a-1)$

$7a^2-14a+7$

$=7(a^2-2a+1)$

$=7[{\left(a\right)}^2-2\left(a\right)\left(1\right)+{\left(1\right)}^2]$

$=7{(a-1)}^2$ ...$[\because {(a-b)}^2=a^2-2ab+b^2]$

$=7(a-1)(a-1)$