integration question (1 Viewer)

[Satiric]

Hey guys,

I need help with this integration question. This is from cambridge 2 unit btw.
Exercise 1D. Q21dii

i keep getting this

thanks in advance

 

[undalay]

hint: (2x+2) integrated = x^2 + 2x

 

[Drongoski]

 

[Trebla]

∫(x + 1)(x² + 2x)² dx = 1/2 ∫(2x + 2)(x² + 2x)² dx
= (x² + 2x)³ / 6 + c
since the derivative of x² + 2x is 2x + 2.
Alternatively, just expand it and integrate if you are unfamilar with reverse chain rule...

 

[undalay]

guys how do u get latex into ur post; i dont get it ):

 

[Satiric]

OMG...integration by sub
didn't think thats even in 2U
anyways thanks a lot guys

 

[Satiric]

guys how do u get latex into ur post; i dont get it ):

same i tried to...doesnt work for me
is it "copy to document"?
coz that just puts it into my quick reply box..

 

[Trebla]

OMG...integration by sub
didn't think thats even in 2U
anyways thanks a lot guys

You were right that integration by substitution isn't in the 2 unit course. In a 2 unit context you would have to apply the reverse chain rule...usually you'll be asked to differentiate (x² + 2x)³ and then derive the integral from it at 2 unit level.

 

[-Onlooker-]

OR you can just expand the expression, then simply differentiate.

 

[Drongoski]

Very good point!

 

[xFusion]

If integration by sub is not in 2u, can you still use it in a 2u exam?

 

[llamaben]

If integration by sub is not in 2u, can you still use it in a 2u exam?

I believe you can use 3u methods, as long as what you've done is still noticeable.

 

[xFusion]

ok thats great because i cannot tell which of my work is 2 or 3u

 

[Prashant Sallan]

Ye, you just expand the equation on the right ( x)^2 , and then expand the equation on the left in. :rofl:

 

[tommykins]

guys how do u get latex into ur post; i dont get it ):

click on a quick reply button.

open latex

type in eqn
copy to document
post.