SOLUTION: Solve. x - 17sqrt(x) + 72 = 0 Again, I know the answer, I just don't know how they got it. Thanks in advance for the help.

Question 853409: Solve.
x - 17sqrt(x) + 72 = 0
Again, I know the answer, I just don't know how they got it.
Thanks in advance for the help.
Answer by richwmiller(17219) (Show Source): You can put this solution on YOUR website!
Share what you know!
factor
x - 17sqrt(x) + 72 = 0
Think of it as y^2+17y+72
what is the square root of y^2 just y of course
we want factors of 72 which add up to -17
(sqrt(x)-9) (sqrt(x)-8) = 0
(sqrt(x)-9)=0
sqrtx=9
x=81
(sqrt(x)-8)
sqrt(x)=8
x=64

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