Question

Find the value of ${998}^2$ by using $(a-b{)}^2$ identity.
$\left[2\right]$

Answer 1

As, 998 =$(1000-2)$
$\therefore (998{)}^2=(1000-2{)}^2$
$\left[1\right]$

This is in the form of $(a-b{)}^2$, we get $a=1000,b=2$

Now, $(a-b{)}^2=a^2-2ab+b^2$
$\begin{array}{cc}(1000-2{)}^2& =(1000{)}^2-2(1000\left)\right(2)+(2{)}^2\\ (998{)}^2& =1000000-4000+4=996004\end{array}$
$\left[1\right]$