Multiplying out brackets
When you multiply out two brackets like this (ax+b)(cx+d)where each bracket has an x term and a constant term, then the result will be a quadratic expression. You will get an x2 term, two x terms, and a constant term.
As a check for your working, when you have done one, make sure you have the right number of terms of each type.
Better, and quicker, is to do the x term in your head. You need to multiply two terms together. In the example above, the co-efficient of x will be ad+bc.
If you can do it in your head and write it straight down, you can save some time and probably some errors. The x2 term is easy enough to do, since it is just the product of the two x co-efficients, and the constant term is the product of the two constant terms.
with a bit of practice, you can write the whole thing down in one step:
abx2 + (ad+bc)x + bd
Exercises
[quadbracketsxl]