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Answer:
a=0
b may be 0 but is not required to be
Explanation:
The y-axis corresponds to the line x=0. Any point on the y-axis will have an x-coordinate of 0.
If (a, b) is on the y-axis, then a = 0.
If the intersection point is (0, 0), then b=0. Otherwise, b is not 0.