Assume that all the given functions have continuous second-order partial derivatives. If z = f(x, y), where x = r2 + s2 and y = 4rs, find ∂2z/(∂r ∂s). (Compare with this example.) ∂2z ∂r ∂s = ∂2z ∂x2 + ∂2z ∂y2 + ∂2z ∂x ∂y + ∂z ∂y

And employee salary increased by $4500 which represents a 15% raise what is the rate of the increase

Avegetable garden and a surrounding path are shaped like a square together are 12 ft wide. the path is 1 feet wide. if one bag of gravel covers 8 square feet, how manu bags are needed to cover the path? round your answers to the nearest tenth.

Solve for x and y: 217x + 131y = 913; 131x + 217y = 827