Question

explain how the next step formed.the one which is rounded,till that I understood,but the last step I didn't understand

Please write in a paper and show.

Answer 1

(b+a) cane written as root over (b+a)^2

root over b^2-a^2=ROOT OVER(b+a)(b-a)

THEREFORE
ROOT OVER(b+a)(b+a)/(b+a)(b-a)=root over(b+a)/(b-a)

Answer 2

♧♧HERE IS YOUR ANSWER♧♧

Now,

$\frac{b + a}{ \sqrt{ {b}^{2} - {a}^{2} } } \\ \\ = \sqrt{ \frac{ {(b + a)}^{2} }{(b + a)(b - a)} } \\ \\ = \sqrt{ \frac{(b + a)(b + a)}{(b + a)(b - a)} } \\ \\ = \sqrt{ \frac{b + a}{b - a} }$

♧♧HOPE THIS HELPS YOU♧♧