How can i find the relative extreme of the ff fun : f(x, y)=x^3+3*x*y^2-15*x^2-15*y^3+72*x

I’m on question 7 it says a covered water tank is in the shape of a cylinder the tank has a 28 inch diameter and a height of 66 inches to the nearest square inch what is the surface area of the water tank

Answer this two poles, ab and ed, are fixed to the ground with the of ropes ac and ec, as shown: two right triangles abc and edc have a common vertex c. angle abc and edc are right angles. ab is labeled 13 feet, ac is labeled 15 feet, ec is labeled 10 feet, and ed is labeled 4 feet. what is the approximate distance, in feet, between the two poles? 11.14 feet16.65 feet14.35 feet15.59 feet

The balance of susu's savings account can be represented by the variable b. the inequality describing her balance b > $30 . which could be a solution to the inequality?