You plug in 1,2,3 and so on in the X and you graph , i think
FOIL this out. 3x*x = 3x^2; 3x*8= 24x; -8*x = -8x; -8*8=-64. Combine like terms to get
15
Explanation:
you just divide 90 by 6
Please check the picture.
The formula for the lateral surface area of a right circular cone is:

where r is the radius of the base, and l is the slant height.
Plugging in the values we get: