Answer:-1
Explanation:
the output of a function is the y value while the input is the x value.
so the question is asking what does the y value( output) have to be for the x value( input) to be zero.
since the graph is provided we can just look to see where the x values becomes zero ( the y axis is when all y values are zero)
we then can identify that the y intercept is -1
hope this helps!!