Question

multi calc

please explain to me how he got from that step to the other?
http://screencast.com/t/G7bD15hGbr

Answer 1

zero product property :

ab = 0
=> a = 0 (or) b = 0 (or) both = 0

Answer 2

3/2 cannot be 0

Answer 3

(x^2 + y^2 + z^2)^(1/2) cannot be 0 either (why ?)

Answer 4

only factor that can be 0 is the one wid partial derivative

Answer 5

I see, now I understand everything ,thanks a lot ganeshie8