SOLUTION: x+2x^1/2-15=0 How is this solve by first writing it as a quadratic equation?

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equation Customizable Word Problems -> SOLUTION: x+2x^1/2-15=0 How is this solve by first writing it as a quadratic equation?      Log On


   

Question 370377: x+2x^1/2-15=0
How is this solve by first writing it as a quadratic equation?
Found 2 solutions by Alan3354, ewatrrr:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
It's a quadratic in x^1/2
Sub y for x^1/2
--> y^2 + 2y - 15 = 0

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi,

x+2x^1/2-15=0

solve by first writing it as a quadratic equation

2x^1/2= 15-x

squaring both sides of the equation

4x = (15-x)(15-x)

4x = 225 - 30x + x^2

x^2 -34x + 225 = 0

factoring

(x-25)(x-9)= 0

(x-25)=0

x = 25

(x-9)= 0

x = 9