Question

What are the zeros of the parabola whose equation is y = x2 + 8x + 15

(1)
-5 and -3
(3)
-5 and 3
(2)
5 and 3
(4)
5 and -3

Answer 1

9514 1404 393

Answer:

(1) -5 and -3

Explanation:

Descarte's rule of signs tells you the lack of sign changes among the coefficients means there are no positive real roots. That eliminates all answer choices except the first one.

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If you want to go to the trouble, you can factor the equation:

y = (x +3)(x +5)

These factors are zero when x = -5 and x = -3.