Let f(x)=(x-1)(x-3)(x+5)+72
Find the sum of all values of x such that f(x)=72 .
The values of x that work are 1 and 3, so the answer is 1 + 3 = 4.
f(x) = 72
(x - 1) ( x - 3 ) ( x + 5) + 72 = 72
(x -1) ( x -3) ( x +5) = 0
x = 1, 3, -5
Sum = -1
.
+8 
