What’s the answer?

Question

What’s the answer? Suppose P varies jointly with u and the square of n. When u=1 and n=5, then P=100. Find P if u=10 and n=8

Answer 1

100 = k(1)5^2 = 25k

k= 100/25 = 4

P = 4(10)(8^2 = 40(64) = 2560

that's assuming direct variation, which is what "joint variation" includes, unless you specify it otherwise.

there's a website showing how to work these joint variation problems

http.//www.mesacc.edu