Question

Find the value of ${4.9}^2$ using a suitable algebraic identity.

• A. 24.01

Answer 1

The correct option is A 24.01
Here,
${4.9}^2$ can be written as $(5.0-0.1{)}^2$
Using the identity $(a-b{)}^2=a^2+b^2-2ab$

Here, a = 5 and b = 0.1
$(5.0-0.1{)}^2=5^2+{0.1}^2-2\times 5\times 0.1$
$(5.0-0.1{)}^2=25+{\frac{1}{10}}^2-1$
$(5.0-0.1{)}^2=25+\frac{1}{100}-1$
$(5.0-0.1{)}^2=25+0.01-1$
$(5.0-0.1{)}^2=24.01$