Expand (x+3)(x+2)
and can you explain how to do it

You multiply the two together
x times x equals x squared ( x^2) the x times 2 which equals 2x, then multiply the 3 and x to get 3x and multiply 3 times 2 = 6
so now your problem looks like x[tex] x^{2} + 2x +3x +6 ( now combine like terms) which gives you x^{2} +5x +6, and thats the answer

Just like the other person said, you distribute. An easy way to remember how is the FOIL method. First, Outside, Inside, Last.
So for F, you'd multiply x and x, making x^2. For O, you'd multiply the first x and the 2, which gives you 2x, then for I, multiply the 3 and the second x, and you get 3x from that. Finally, for the L, multiply the 3 and 2, which is 6.
When the whole thing is "foiled," you end up with
x^2 + 2x + 3x + 6.
To put it in its simplest form, combine like terms. In this case, the 2x and 3x.
When you're finished, the expanded form should look like
x^2 + 5x + 6.
I hope that helped!