Answer:

Step-by-step explanation:
Given:

Required
Rewrite in vertex form
The vertex form of an equation is in form of: 
Solving: 
Subtract 2 from both sides


Factorize expression on the right hand side by dividing through by the coefficient of x²


Get a perfect square of coefficient of x; then add to both sides
------------------------------------------------------------------------------------
<em>Rough work</em>
The coefficient of x is 
It's square is 
Adding inside the bracket of
to give: 
To balance the equation, the same expression must be added to the other side of the equation;
Equivalent expression is: 
------------------------------------------------------------------------------------
The expression becomes



Factorize the expression on the right hand side





Make y the subject of formula

<em>Solved</em>
The second option
(Pie x 2.5 squared x height)
Answer:
r^2=(A/pi)
Step-by-step explanation:
if A=pi*r^2 then maybe dividing by pi to get r^2 alone says r^2=(A/pi) or to get rid of the exponent you may square root each side so r=(sqrt(A/pi))
I believe the answer is B.