Question

20x^3-16x^2+4x

Answer 1

What are we supposed to do with this? Simplify?

Answer 2

Erm... factor, I mean?

Answer 3

factor - 25x^3-20x^2+5x

Answer 4

Alright, first thing we want to do is this: Tell me what common factor is in each of the coefficients?

In other words, what's the biggest positive number you can divide -25, -20 and 5 by?

Answer 5

5?

Answer 6

yup

Answer 7

Excellent. Now, is there a common variable (letter) in all of them?

Answer 8

if u pull out a 5, what r u left w/ ??

Answer 9

yes x

Answer 10

pull out a 5x

Answer 11

whats left in the parenthesis

Answer 12

25x^3-20x^2?

Answer 13

first pull out a 5x from -25x^2. what do u get

Answer 14

oops i meant -25x^3

Answer 15

Good guess, but what we put in the parentheses is what we have to multiply to get the original. For example:

let's say we had 10x+5

5 is the only common factor.
So, we'd have 5(2x+1)
Because when you multiply it all out again, you get 10x+5

Answer 16

Careful:
5x(-25x^3) = -125x^4

What you want to do is find ??? in the equation:
5x(???) = -25x^3

Answer 17

First of all, 5 times what equals negative 25?

Answer 18

pull out 5x from -25x^3, ur left with -5x^2. pull out 5x from -20x, ur left w/ -4x. pull out 5x from 5x and ur left w/ 1.

Answer 19

So to reinforce what mathballet said, when you multiply 5x(-5x^2 -4x + 1). you get your original expression back.

Answer 20

uber-should we just spill whats left in the parenthesis

Answer 21

or should we explain how 2 factor the -5x^2-4x+1

Answer 22

Alas, I've already done that lol. You could double check that she understands it by offering a similar equation. I'm heading to bed, but perhaps this is a good thing to test out:

Factor out the following: 40x^4 + 30x^2 - 50x

Answer 23

Whooops, I posted too slowly. By "I've already done that", I meant I spilled what's in the parentheses.

Answer 24

10x(4x^3+3x-5)