Quick question (multiple choice). HELP please!?

Question

Given (x – 3)^2 + (y + 1)^2 = 16. If x and y are differentiable functions of t, determine dx/dt.

a) 2(y + 1)*dy/dt
b) –[(y + 1)/x – 3]
c) –[(y + 1)(dy/dt) / x – 3
d) –[x – 3/y + 1]

Answer 1

Differentiate and get

2(x-3) dx/dt + 2(y+1) dy/dt = 0
dx/dt = [-2(y+1) dy/dt] / [2(x-3)]
dx/dt = [-(y+1) dy/dt] / (x-3)

which would be c) if you hadn't dropped the ] .

Answer 2

write Q's properly