# Math Help - range

1. ## range

given that f(x,y) =30xy^2 for x-1<y<1-x and 0<x<1. find F(0.5,0.5)

i know that we need to do double integration and i tried to integration from -0.5 to (1-x) dy followed by integration from 0 to 0.5 dx..but my answer was wrong...

may i know what is wrong with my understanding of this question?

thanks!

2. Originally Posted by alexandrabel90
given that f(x,y) =30xy^2 for x-1<y<1-x and 0<x<1. find F(0.5,0.5)

i know that we need to do double integration and i tried to integration from -0.5 to (1-x) dy followed by integration from 0 to 0.5 dx..but my answer was wrong...

may i know what is wrong with my understanding of this question?

thanks!
$\int_{x=0}^{0.5} \int_{y=x-1}^{0.5} f(x,y)\; dydx$

CB

3. how do you decide that tHe lower limitt for y is x-1 and not jusT -1?does the first integration usually involve a variable?

sorry im new to this chapter so im still nt sure how im suppose to find the limts.
thanks.

4. Originally Posted by alexandrabel90
how do you decide that tHe lower limitt for y is x-1 and not jusT -1?does the first integration usually involve a variable?

sorry im new to this chapter so im still nt sure how im suppose to find the limts.
thanks.
The range of y is specified in terms of x so y should be the inner integral, leaving x as the outer integral.

CB

5. if i want to find F(o.5,2)

would the double integral be from x-1 to 1-x for dy and then followed by x=0 to 0.5 for dx?

thanks!