Question

Using identities, find the value of $(4.5{)}^2$.

• A. 20
• B. 20.25
• C. 19.25
• D. 19

Answer 1

The correct option is B 20.25

$(4.5{)}^2$ can be written as $(5.0-0.5{)}^2$
This is in the form of $(a-b{)}^2$ where, a= 5 and b = 0.5
We know that,
$(a-b{)}^2=a^2+b^2-2ab$
$(4.5{)}^2=(5{)}^2+(0.5{)}^2-2(5\left)\right(0.5)$
$=25+0.25-5$
$\Rightarrow$ 20.25
Hence, the value of $(4.5{)}^2$ is 20.25.