How is the 4 in 864 related to the 4 in 846

Solve the system of equations. y= 2x y= x^2 - 15

Aswimming pool is a rectangle with semicircles on the end. the rectangle is 12 meters wide and 30 meters long. the diameter and width of the swimming pool are equal. sketch and label an overhead diagram of the swimming pool. find the area of the swimming pool floor.

If f(x)=-x^2+6x-1 and g(x)=3x^2-4x-1,find(f+g)(x)