Question

If $a+b=0.9$ and $ab=0.36$; find:
(i) $a-b$
(ii) $a^2-b^2$

Answer 1

Given that,

$\begin{array}{c}a-b=0.9\\ ab=0.36\end{array}$

Now,

We know that,

$\begin{array}{c}{\left(a-b\right)}^2={\left(a+b\right)}^2-4ab\\ {\left(a+b\right)}^2={\left(0.9\right)}^2+4\left(0.36\right)\\ =0.81+1.44\\ =2.25\\ a+b=1.5\\ a^2-b^2=\left(a+b\right)\left(a-b\right)\\ =\left(1.5\right)\left(0.9\right)\\ =1.35\end{array}$