Question

find ∂f/∂x in ( 4,–5 ) when
f(x,y) = x^ 2 + 3xy + y – 1

Answer 1

Show me your best guess and lets go from there.

Answer 2

Since this is the partial derivative, it looks at how x-changes with respect to the function. It doesn't take any consideration as to what y does, and leaves y as a constant.

Answer 3

2x+3y??

Answer 4

Yes exactly! now what?

Answer 5

2(4)+3(-5)??

Answer 6

Yep. Now you solve, that's it, really.

Answer 7

-7

Answer 8

You got it.

Answer 9

but the next exercise is the same but it is find ∂f/∂y in stead of find ∂f/∂x is it the same answer?

Answer 10

It will be similar, but you'll be treating the y's as your variable of integration and x's as constants. It will be similar, but not the same answer.

Answer 11

-15?