SOLUTION: 7) The correct solution to 3=2√x+x is: a. x=1 and x=3 b. x=1 and x= 4 c. x=1 and x=9 I can not figure this out...this is what I keep getting: 3=2√x+x 9=4x+

Algebra ->  Radicals -> SOLUTION: 7) The correct solution to 3=2√x+x is: a. x=1 and x=3 b. x=1 and x= 4 c. x=1 and x=9 I can not figure this out...this is what I keep getting: 3=2√x+x 9=4x+      Log On


   



Question 11339: 7) The correct solution to 3=2√x+x is:

a. x=1 and x=3
b. x=1 and x= 4
c. x=1 and x=9
I can not figure this out...this is what I keep getting:
3=2√x+x
9=4x+x²
x²+4x-9=0
And my answer does not factor into any of the possible answers, so I am completely stuck. Can you help me?

Answer by longjonsilver(2297) About Me  (Show Source):
You can put this solution on YOUR website!
you have done THE classic error when squaring. You cannot square each term...you square EACH SIDE, so you would have:

%283%29%5E2=%282sqrt%28x%29%2Bx%29%5E2 which will be horrible to expand.

The secret is to get the term with the square root in it by itself and THEN square both sides, as follows.

3=2sqrt%28x%29%2Bx
3-x=2sqrt%28x%29

Now square both sides, to give %283-x%29%5E2=4x
9-6x%2Bx%5E2=4x
x%5E2+-+10x+%2B+9+=+0
(x-9)(x-1) = 0
--> x-9=0 OR x-1=0
so x=9 or x=1

jon.