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∫sec²(4x+1)dx

∫1/ 2cos²x  dx

∫cosec3x cot3x  dx

∫cot²x  dx

∫tan²2x  dx

∫(1+cosx)²  dx

please help me find all six of these!

thankyou so much

 Jan 26, 2015

Best Answer 

 #1
avatar+118724 
+5

 

 

I'll look at the first one.

∫sec²(4x+1)dx

The first thing that you need to know is that the integral of tan x is sec2x

My strategy is to work backwards from there.

 

$$\\\frac{d}{dx}tan(4x+1)=4sec^2(4x+1)$$

 

Mmm I need to get rid of that pesky 4 so

 

$$\\\frac{d}{dx}\frac{tan(4x+1)}{4}=\frac{4sec^2(4x+1)}{4}=sec^2(4x+1)\\\\$$

 

so

 

$$\int{sec^2(4x+1)dx=\frac{tan(4x+1)}{4}+c$$

 Jan 27, 2015
 #1
avatar+118724 
+5
Best Answer

 

 

I'll look at the first one.

∫sec²(4x+1)dx

The first thing that you need to know is that the integral of tan x is sec2x

My strategy is to work backwards from there.

 

$$\\\frac{d}{dx}tan(4x+1)=4sec^2(4x+1)$$

 

Mmm I need to get rid of that pesky 4 so

 

$$\\\frac{d}{dx}\frac{tan(4x+1)}{4}=\frac{4sec^2(4x+1)}{4}=sec^2(4x+1)\\\\$$

 

so

 

$$\int{sec^2(4x+1)dx=\frac{tan(4x+1)}{4}+c$$

Melody Jan 27, 2015

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