Question

What are the zeros of the polynomial function: f(x) = (x + 3)(x – 1)(x + 5)?

3, 1, –5

–3, 1, –5

3, –1, 5

–3, –1, 5

Answer 1

if any one of those 3 sets of parentheses has a zero value, then the whole function is zero.

So what x values create a value of zero inside any one of the sets of parentheses?

Like the first one... (x+3)... what "x" makes (x+3) = 0 ?

Answer 2

wut?

Answer 3

the first part of the function is (x+3)... if you evaluate f(x) at x = -3, then that first part becomes (-3 + 3) = 0 and so it doesn't matter what the rest of the parts of the function are, f(-3) is going to be 0.

Answer 4

so does that leave only a and d?

Answer 5

x = -3 appears in b and d, not a and d...

Yes, so then for the other two "zeros", just look at the "x" value you need to make the 2nd and 3rd parenthesis equal 0.

(x-1) = 0 <------- x = ?
(x+5) = 0 <-------x = ??

Those x values are the other two "zeros" of the function.

Answer 6

yea sorry, so D!

Answer 7

no, "b" :)

x must be 1 to make (x-1) = 0, and x must be -5 to make (x + 5) = 0

It's just backwards from the way you were thinking...

Answer 8

@andreadesirepen

Answer 9

oh, im dumb. thanks!!

Answer 10

not dumb, just in a hurry, I bet... glad to help :)