3.141562.... And it goes on and on and on
The answer is either
or 
To solve: Let's solve your equation step-by-step.
5x2+5x−x2−x=2004
Step 1: Simplify both sides of the equation.
4x2+4x=2004
Step 2: Subtract 2004 from both sides.
4x2+4x−2004=2004−2004
4x2+4x−2004=0
Step 3: Use quadratic formula with a=4, b=4, c=-2004.
x=
−b±√b2−4ac
/2a
x=
−4±√32080
/8
or 
let's recall the vertical line test, if a vertical line hits the graph or points twice, then is NOT a function. Check the picture below.
3(2x-4)=2(x+4)
6x-12=2x+8
6x-2x=8+12
4x=20
x=20/4
x=5
15 units because I need to have