How do you factor: #y= x^3 + x^2 − 20x #?

1 Answer
Dec 2, 2015

Answer:

Factor #y = x^3 + x^2 - 20x#

Explanation:

#y = xY = x(x^2 + x - 20)#. Factor #Y#

Find 2 numbers knowing sum (1) and product (-20).
Factor pairs of #-20 -> (-2, 10)(-4, 5)#. This sum is #-4 + 5 = 1 = b#.

Therefore, the 2 numbers are #-4# and #5#.

Factored form:

#y = xY = x(x - 4)(x + 5)#