Answer:
it is equals to 3 okay ^^
The y intercept is 0, and the slope is 5x.
Equation: y = 5x +0.
One way to do this is use the fact that the exterior angles of all polygons add up to 360 degrees
So an exterior angle of a regular octagon = 360 / 8 = 45 degrees.
So each interior angle = 180 - 45 = 135 degrees
so total measure of all angles in octagon = 8 * 135 = 1080 degrees
That would be the cube root of (x+5)^11.
If desired, this could be reduced to the cube root of (x+5)^9*(x+5)^2, which would be
(x+5)^3*(x+5)^(2/3)