Question

Check my answer? Four polynomial functions are shown below:

f(x) = x^3 + 3x^2 - 4x - 12
g(x) = x^3 - 3x - 2
p(x) = x^2 + 3x + 2
t(x) = x^2 + x - 2

Which of the following functions has 1 and -2 as its zeros?

f(x)
g(x)
p(x)
t(x)

Answer 1

1 think its g(x) but 1'm not sure.

Answer 2

@SolomonZelman @freckles

Answer 3

If you think g(x) is the correct function, then g(1) and g(-2) must both equal zero.

Answer 4

Do you know how to find g(1) and g(-2)?

Answer 5

1 think so...

Answer 6

you just input 1 or -2 for x right?

Answer 7

both g(1) and g(-2) are -4, if 1 did that correctly.

Answer 8

You can program the functions into your calculator and then check that way if you have a TI calc.

Answer 9

1 have a T1 calculator but 1'm not sure how to do that. By T1 you mean Texas 1nstument right?

Answer 10

Yes. If you don't have a TI-Nspire, then you'll have to find your calc guidebook in order to figure out how to program functions into your calc. I only know how to do it for TI-Nspire series.

Answer 11

But g(1) and g(-2) are both -4 so g(x) is not the right function.

Answer 12

Oh

Answer 13

Now that you know how to do this, you should be able to use the same approach to find the correct function.

Answer 14

1 know its not f(x)...

Answer 15

We can definitely eliminate p(x) because p(1) won't work to find zero.

Answer 16

This we can figure out by observation since adding positive numbers will never yield zero.

Answer 17

ohhh its t(x)

Answer 18

sorry I didn't even see that one.

Answer 19

The correct answer is t(x) and you could have also figured it out by observation as well. Great job.

Answer 20

Thanks so much!