Question

Determine the values of x for which f'(x)=0, given that f(x)=2x/(1+4x^2).

Answer 1

Derivative is (-8x^2+2)/(1+4x^2)^2.

Answer 2

then set the numerator equal to zero and solve

Answer 3

I know, but I'm getting confused on how to separate x and whatnot.

Answer 4

\[8x^2=2\]
\[x^2=\frac{1}{4}\]
\[x=\pm\frac{1}{2}\]

Answer 5

Oh, numerator only you said.

Answer 6

yea, fraction is only zero when numerator is

Answer 7

Is that always the case when you are looking for a value of a fraction that equals zero?

Answer 8

sure, just like with numbers right?

Answer 9

an x value that is

Answer 10

\[\frac{0}{b}=0\]

Answer 11

Yep, true. Ok makes sense. Thanks.