Finding zeros (math homework)

[lukevanoort]

Originally Posted by VEN

So say my relation is A = w(20-w), I'd solve that by making w=0 and 20-w = 0? So all this is, is substitution? Guess and check?

Well you distribute w(20-w) to 20w-w^2, then subtract A, so you get
-w^2+20w-A=0. Then you use the quadratic formula so it goes in as
(-20 (+/-) sqrt(400-4(-1)(-A)))/-2 which simplifies to (-20 (+/-) sqrt(400-4A))/-2 you can factor a 4 out of (400-4A) so it becomes 4(100-A). The sqrt of 4 is two, so you get (-20 (+/-) 2 sqrt(100-A))/-2. You can divide the -20 and the 2 by the -2 so your final answer is 10 (+/-) sqrt(100-A).

PS Can someone check me on that? I'm a bit sleepy.