# Can someone please break this down for me?

• December 6th 2008, 08:36 PM
HappyFeet
Can someone please break this down for me?
X= -4√x+12
(Shake)
• December 6th 2008, 08:49 PM
Shyam
Quote:

Originally Posted by HappyFeet
x= -4√x+12
(Shake)

$x-12=-4\sqrt x$

now, squaring both sides and solve the quadratic eqn.
• December 6th 2008, 08:51 PM
mr fantastic
Quote:

Originally Posted by HappyFeet
X= -4√x+12
(Shake)

What are you trying to do? Solve for x? Then:

$x = -4\sqrt{x} + 12 \Rightarrow x - 12 = -4 \sqrt{x} \Rightarrow (x - 12)^2 = 16x \Rightarrow x^2 - 40x + 144 = 0$.

One of the solutions to this equation is the solution to $x = -4\sqrt{x} + 12$, the other is not (it's an extraneous solution and is in fact the solution to $x = 4\sqrt{x} + 12$).