2007-04-16 12:12:47 · 6 answers · asked by andrew 3 in Science & Mathematics ➔ Mathematics
x³-2x²-15x = x·(x² - 2x - 15) = x·(x-5)·(x+3)
Explanation.
1.) Take out x (it is the common factor of x³, 2x² and 15x.
2.) Factorize (x² - 2x - 15) into (x+a)·(x+b).
Choose a and b so that a·b = -15 and a-b = -2.
Hope this helps.
2007-04-16 12:15:37 · answer #1 · answered by M 6 · 4⤊ 0⤋
x^3-2x^2-15x
take out x
x (x^2 - 2x - 15)
factor the rest. Look for two numbers that multiply to -15 and add to -2.
the two numbers are -5 and 3
x (x-5) (x+3)
2007-04-16 12:16:20 · answer #2 · answered by 7 · 0⤊ 0⤋
factor out x first:
x(x^2 -2x -15)
then factor the quadratic:
x(x - 5)(x + 3)
2007-04-16 12:16:46 · answer #3 · answered by dharmabum2 2 · 0⤊ 0⤋
x(x-5)(x+3)
2007-04-16 12:17:00 · answer #4 · answered by je t'♥ 5 · 0⤊ 0⤋
x^3-2x^2-15x
1) take out x....it becomes
x(x^2-2x-15)=0
2) then...
x[(x-5)(x+3)]=0
3) solution
x=o, 5 or -3
2007-04-16 12:17:59 · answer #5 · answered by Anonymous · 0⤊ 0⤋
x^3-2x^2-15x
x(x^2-2x-15)
x(x+3)(x-5)=0
x=-3;x=5 x=0
2007-04-16 12:18:49 · answer #6 · answered by Dave aka Spider Monkey 7 · 0⤊ 0⤋