9514 1404 393
Answer:
input: 0 or -4
Explanation:
Given:
c(y) = y² +4y
Find:
y such that c(y) = 0
Solution:
0 = y² +4y . . . . . desired condition
0 = y(y +4) . . . . . factor
We have the product of two factors. The "zero product rule" tells us that the product is only zero if one or more of the factors is zero.
y = 0 . . . . . makes the factor y be zero
y = -4 . . . . . makes the factor (y+4) be zero
The inputs you're looking for are 0 or -4.