Question

Compute the value of ${\left(6\frac{1}{2}\right)}^2-{\left(4\frac{1}{2}\right)}^2$

• A. 24
• B. 22
• C. 21
• D. 25

Answer 1

The correct option is B

22

The given expression is

${\left(6\frac{1}{2}\right)}^2-{\left(4\frac{1}{2}\right)}^2$ which can be written as

$=(6\frac{1}{2}+4\frac{1}{2})(6\frac{1}{2}-4\frac{1}{2})[a^2-b^2=(a+b\left)\right(a-b\left)\right]$

$=11\times 2$

$=22$