Step-by-step explanation:
[tex]a = \sqrt{b - a} [/tex]
firstly square
[tex] \sqrt{b- a} [/tex]
to get a-b on it's own
it's now
[tex]a = b - a[/tex]
now plus the a to cancel out the minus a to get
[tex]a {}^{2} = b[/tex]
which can also be written as
[tex]b = a {}^{2} [/tex]
dont know if that makes sense as I'm not the best at trying to explain