Question 754080
A = P(1 + r)^2
First of all square root both sides
this gets rid of the square on the right.

Square rootA = P(1 - r)

Divide both sides by P
This gets rid of the P 
on the right

Square root A/ P = 1 - r
 Take away 1 from both sides
This gets rid of the 1 on the right.

(square root A)/P - 1 = - r

Finally multiply both sides by -1
This makes r positive.

  r = 1 - (square rootA)/ P

Hope this helps
:-)