Question

Using suitable algebraic identity, find the value of ${\left(4.9\right)}^2$.

• A. 24.01
• B. 25
• C. 24
• D. 24.25

Answer 1

The correct option is A 24.01

${\left(4.9\right)}^2$
= ${(5.0-0.1)}^2$

Using the identity: $(a-b{)}^2=a^2-2ab+b^2$ we get
${(5.0-0.1)}^2$
= ${\left(5\right)}^2$ - $2\left(5\right)\left(0.1\right)$ + ${\left(0.1\right)}^2$
= $25+0.01-1$
= $24.01$