# Thread: help needed to rearrange equation

1. ## help needed to rearrange equation

Can you please help me rearrange this equation and make z the subject:

x = z +1/4z

2. Start by adding like terms. This becomes x = 5z/4. Now divide both sides by 1.25. You have z = 4x/5

EDIT Sorry, should have been x = 5z/4

3. Multiply both sides by 4 to get $4x = 4z + z = 5z$ therefore $z = 4/5x$

4. Both satx and Amber Lamps assumed that you mean x= z+ (1/4)z.

If you meant, instead, x= z+ 1/(4z), multiply the entire equation by 4z to get $4xz= 4z^2+ 1$ which is the same as $4z^2- 4xz- 1= 0$.

Solve that with the quadratic formula: $z= \frac{-b\pm\sqrt{b^2- 4ac}}{2a}$
with a= 4, b= -4x and c= -1.

5. Thanks everyone that has been a real help