Question

I can't use a calculator for this question so i need HELP.

find the x-intercepts of f(x)= x^3- 2x^2 -x +2

Answer 1

Ah! This is easy peasy my dear :) Factor by grouping and then find the zeros!

Answer 2

If you need me to be more in depth, I can show you step by step.

Answer 3

yes please, step by step would be nice :)

Answer 4

.....

Answer 5

Sure!
x^3 - 2x^2 - x + 2 = 0
(x^3 - x) (- 2x^2 + 2) = 0 <-- All I did here was rearrange the terms & put them in ( )
x(x^2 -1) -2(x^2 - 1) = 0 <-- Factor
(x - 2)(x^2 -1) = 0 <-- Just grouping again
x - 2 = 0 --> x = 2 <-- Setting them equal to zero
x^2 - 1 = 0 --> x^2 = 1 <-- Now square root both sides
x = 1
Your intercepts are x = 1 and 2 :) I hope you understood that!

Answer 6

It might be a bit difficult for you to read typed up like this, but I can show you in a whiteboard room if you'd like.

Answer 7

use first synthetic division if you know that

Answer 8

@agentNao thank you so much ill take it from here :)

Answer 9

You're very welcome! I hope I was of some help :)

Answer 10

x = -1 is also a solution.

Answer 11

Cubics have 3 solutions :)

Answer 12

Oops! Sorry about that. Dangolberry is very right. When you square root something, you'll always have a plus and minus of the answer.

Answer 13

so just to clarify,
x=+-1 and +-2?

Answer 14

x = 1, x = -1 and x = 2

Answer 15

It's not +- 2 because we didn't have to square root that.

Answer 16

right!