To find the y intercept you must substitute 0 into x.
F(x) = (-3x0) - (6x0) - 5
F(x) = -5
To find the axis of symmetry and vertex we use the formula -b/2a to find the x coordinate
x = 6/(-3x2)
x = 6/-6
x = -1
Now we need to find the y coordinate so we sub -1 into x.
F(x) = (-3x-1) - (6x-1) - 5
F(x) = 3 + 6 - 5
F(x) = 4
The axis of symmetry and vertex are (-1,4) and the y coordinate is -5. Hope this helps.
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