Pre-Calculus help?

0 ⤊

Find the zeros of this function f(x)= x^3-4x^2-25x+100

2007-07-22 12:25:28 · 2 answers · asked by oscarjr1990 2 in Science & Mathematics ➔ Mathematics

2 answers

f(x)= x^3-4x^2-25x+100
= x^2(x-4) -25(x-4)
=(x^2-25)(x-4)
=(x-5)(x+5)(x-4)
So roots are 5,-5, and 4

2007-07-22 12:31:12 · answer #1 · answered by ironduke8159 7 · 0⤊ 0⤋

group the numbers together like this
f(x) = x^3 - 25x - 4x^2 + 100
f(x) = x(x^2 - 25) - 4(x^2 - 25)
f(x) = (x - 4)(x^2 - 25)
f(x) = (x - 4)(x + 5)(x - 5)

ANSWER
x = -5, 4, 5

2007-07-22 19:34:57 · answer #2 · answered by trackstarr59 3 · 0⤊ 0⤋