Of course you have to rearrange it

Question

X -Xo = (V-Vo)(V+Vo)/2a
(X-Xo)2a = (V-Vo)(V+Vo)
2 a (X-Xo) = V^2-Vo^2

ok to go from the first line to the second line you multiply by 2a I agree but what allows you to just put parenthsess around the X-Xo

Thank You!

Answer 1

You muliplied both sides by 2a..

2a(x-xo)=2a(V-vo)(V+vo)/2a
2a(x-x0)=(v-vo)(v+vo)