# integration helpWatch

#1

how do u integrate
(5x+2).sqrt((x^2)-3)?
0
9 years ago
#2
5x.sqrt(x^2 - 3) is a straightforward enough sub. you're prob ok there?

now for 2sqrt(x^2 - 3)

3cosh^2u - 3 = 3sinh^2u

and coshu differentiatess to sinhu so you can see what i'm getting at?
0
#3
(Original post by Rocious)
5x.sqrt(x^2 - 3) is a straightforward enough sub. you're prob ok there?

now for 2sqrt(x^2 - 3)

3cosh^2u - 3 = 3sinh^2u

and coshu differentiatess to sinhu so you can see what i'm getting at?

cool, thank u. i wasnt expecting to use 2 diff methods.

could u also help with this one

(2x^2 + 1)sqrt(5-x)...
0
9 years ago
#4
i'd go parts with u = 2x^2 + 1 and dv = sqrt(5 - x) dx

2x^2 + 1 gets "simpler" when differentiated and sqrt(5 - x) doesn't really become harder to work with whether you differentiate or integrate.. it's still in the form of (ax + b)^n which is always nice. think with parts you just need to get a feel for it through doing it a lot.
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