Find the number of integer solutions of

1) x1 + x2 +x3 + x4= 15

x1 >1, x2 >0, x3 > 1, x4> 2

2) x1 + x2 + x3 + x4 =12

xi >0, i= 1,2,3,4.

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- Oct 13th 2009, 09:59 AMLAURA.GOODMANHomework help
Find the number of integer solutions of

1) x1 + x2 +x3 + x4= 15

x1 >1, x2 >0, x3 > 1, x4> 2

2) x1 + x2 + x3 + x4 =12

xi >0, i= 1,2,3,4. - Oct 13th 2009, 10:40 AMSoroban
Hello, Laura!

Here's the second one . . .the easier of the two.

Quote:

Find the number of integer solutions of: .

Consider 12 objects in a row; leave a space between them.

. .

There are 11 spaces.

We choose 3 of them to insert "dividers."

So that: .

. . And: .

Therefore, there are: . solutions.