<PRE><B>Question 885409</B>
5 -square root(x+7) = square root(x-8)
5 = square root(x-8) + square root(x+7)
square both sides of =
25 = (x-8) +2square root(x-8)square root(x-7) +(x+7)
25 = 2x +2square root(x-8)square root(x-7) -1
add 1 to both sides of =
26 = 2x +2square root(x-8)square root(x-7)
divide both sides of = by 2
13 = x +square root(x-8)square root(x-7)
subtract x from both sides of =
13-x = square root(x-8)square root(x-7)
use square root rule, square root(ab) = square root(a)squar root(b)
13-x = square root((x-8)(x+7))
square both sides of =
169-26x-x^2 = (x-8)(x+7)
169-26x-x^2 = x^2-x-56
-25x = -225
x = 9
answer is C

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