Question

Which linear expression is a factor of this polynomial function?
f(x) = x^3 + 3x^2 – x – 3

Answer 1

A) x-1
B) x+1
C) x+3
D) x-3

Answer 2

f(1) =?

Answer 3

replace 1 into f

Answer 4

knock knock, last attempt: f(1) =?

Answer 5

I don't see what I'm supposed to do with that.

Answer 6

just answer me, you can see after then.

Answer 7

f(1) = 1^3 + 3(1^2) – 1 – 3?

Answer 8

yup, =?

Answer 9

0?

Answer 10

Bingo,

Answer 11

f(1) =0, that shows 1 is a root of the expression. In other words, (x-1) is a factor or f(x) . Done

Answer 12

Ah, alright. Why is it x-1 rather than x+1?

Answer 13

If you take x+1, that is the root is -1, not 1, \(f(-1) = (-1)^3 +3(-1)^2 -1-3= -2\neq 0\)

Answer 14

Got it. Thank you very much. :-)

Answer 15

hehehehe.. sometimes, be patient to get a good trick is ok, right?

Answer 16

Indeed! At first, I thought I was just misunderstanding what you wanted me to do.