Expand (X+5)(2X+3)
When you are expanding a double bracket you have to multiply each each in one bracket against the two others terms in the other bracket. So starting with X: X times the first term in the other bracket which is 2X equals 2X2 and X times the second term in the bracket which is 3 equals 3X. You use the same process for the second term in the first bracket: so 5 times 2X equals 10X and 5 times 3 equals 15.Now we have 4 different equations with 4 different answers: 2X2, 3X, 2X and 15. Now you collect like terms, starting with the X2 terms, here we only have 2X2 so that stays as it is. We collect X terms, now we have two terms 10X and 3X so you simply add them together to get 13X. Finally we look at the unit terms and here there is only 15, so that stays as it is. SO the final answer is 2X2+13X+15.
