How to solve this is by plugging in each x and y into the equation. f(x) means the exact same thing as y. If the answer equals each other then the point is on the line
Part A:
x = 3
y or f(x) = -4
-4 = -3(
) + 6(3) + 5
-4 = -3(9) + 18 + 5
-4 = -27 + 18 + 5
-4 = -9 + 5
-4 = -4 ------------------------------------------------->This point (3, - 4) is on the line
Part B:
x = -1
y or f(x) = 4
4 = -3(
) + 6(-1) + 5
4 = -3(1) - 6 + 5
4 = -3 - 6 + 5
4 = -9 + 5
4 = -4 ------------------------------------------------->The point (-1, 4) is NOT on the line
You can use a graph to check it, which I provided below.
Hope this helped!