Question

Evaluate the below expression using identities:
$(b-7{)}^2$

• A. $b^2-14b+49$
• B. $b^2+14b+49$
• C. $b^2+49-14b$
• D. $b^2-14b-49$

Answer 1

Answer: (A), (C)

The correct options are
A $b^2-14b+49$
C $b^2+49-14b$

$(b-7{)}^2=(b{)}^2-2\times b\times 7+(7{)}^2$
$\left[Usingidentity\right(a-b{)}^2=a^2-2ab+b^2]$
$=b^2-14b+49$