Iterated Integral

[KEYWEST17]

So far I have (x+y)^-2

Used U substitution

U=x+y
DU= 0+1 dx


y=3 to y=4 (U^-2) DU = U^-1/-1

(x+y)^-1/-1 from y=3 to y=4

From this point on I am stuck.

 

[tkhunny]

$\displaystyle \int \frac{1}{(x+y)^{2}}\;dx\;=\;-\frac{1}{x+y} + f(y)$

$\displaystyle \int \frac{1}{(x+y)^{2}}\;dy\;=\;-\frac{1}{x+y} + g(x)$

Why are you substituting anything?