Thursday

July 24, 2014

July 24, 2014

Posted by **gnozahs** on Wednesday, June 10, 2009 at 11:42pm.

I used the quotient rule and got (sec^2x-4)(secx)-(tanx-4)(cosx)/sec^2x but I'm pretty sure that's wrong. Help. Thanks.

- Calculus -
**MathMate**, Wednesday, June 10, 2009 at 11:52pmIt is not clear what your expression really is, there are two possibilities. In both cases, it pays to do a little simplification before differentiating.

If f(x)=(tan(x)-4)/sec(x)

then

f(x)

=tan(x)*cos(x) - 4 cos(x)

=sin(x) - 4 cos(x)

f'(x) = cos(x) + 4 sin(x)

If f(x) = tan(x) - 4/sec(x)

then

f(x) = tan(x) - 4 cos(x)

f'(x) = sec^{2}(x) + 4 sin(x)

- Calculus -
**gnozahs**, Wednesday, June 10, 2009 at 11:58pmcos(x) + 4 sin(x) is correct. How did the 4 end up with the sin and not with the cos?

- Calculus -
**MathMate**, Thursday, June 11, 2009 at 12:05amIt comes from

-4/sec(x) = -4 cos(x)

So when differentiated, it gives 4 sin(x)

**Related Questions**

calculus - find dy/dx y=ln (secx + tanx) Let u= secx + tan x dy/dx= 1/u * du/dx ...

Calculus - Integration - Hello! I really don't think I am understanding my calc ...

Calculus - Int tanx sec^2x dx can be taken as (by putting it in form of Int xdx...

math - 1. (sinx/cscx)+(cosx/secx)=1 2. (1/sinxcosx)-(cosx/sinx)=tanx 3. (1/1+cos...

Pre-Calc - Trigonometric Identities Prove: (tanx + secx -1)/(tanx - secx + 1)= ...

precal - 1/tanx-secx+ 1/tanx+secx=-2tanx so this is what I did: =tanx+secx+tanx-...

Calc - Hello im trying to integrate tan^3 dx i have solved out the whole thing ...

Calc - Hello im trying to integrate tan^3 dx i have solved out the whole thing ...

precal- PLEASE HELP! - secx/secx-tanx=sec^2x+ secx+tanx

Math - I can't find the integral for (tanx)^(6)*(secx)^(2) I tried splitting up ...