Question

20 POINTS PLEASE HELP

Identify a zero of the function x^2+2x-3
a) -3
b) -1
c) 0
d) 2

Answer 1

a) -3

Explanation:

Zero of a function is the x-value where y = 0

x² + 2x - 3 = 0

x² + 3x - x - 3 = 0

x(x + 3) - (x + 3) = 0

(x - 1)(x + 3) = 0

x = 1, -3

Answer 2

A

Explanation:

Essentially, if we plug in any of the given choices into the function and we get 0, then that's our answer.

A) (-3)^2 + 2 * (-3) - 3 = 9 - 6 - 3 = 0 - correct

B) (-1)^2 + 2 * (-1) - 3 = 1 - 2 - 3 = -4 - incorrect

C) 0^2 + 2 * 0 - 3 = -3 - incorrect

D) 2^2 + 2 * 2 - 3 = 4 + 4 - 3 = 5 - incorrect

So, the answer is A.

The alternative, more "formal" way of doing this problem is to factor the quadratic: x^2 + 2x - 3 = (x + 3)(x - 1) = 0

Then set each of these equal to 0: x + 3 = 0 and x - 1 = 0

We get the values of x = -3 and x = 1. Only -3 is one of the answer choices, so A is correct.

Hope this helps!