C1 Topic 2: Algebra
Expanding brackets 1
A quadratic function is one that contains terms including x^2. It may include terms including x and constant terms. It cannot contain x^3 or higher powers. Expanding brackets is a common technique in A level mathematics. You might know about the FOIL method (see below). (x + 3)(x+2) = x^2 +2x + 3x + 6 = x^2 + 5x + 6 Use the interactive display to see how the expression (ax+b)(cx+d) is multiplied out. You can change the quadratic function and then see the process, step by step.

Summary Multiplying out brackets is such an important part of A Level mathematics. You must practise until you can do it quickly, accurately and reliably. One handy way of remembering how to do this is the "FOIL method" (x + 3)(x + 2) First - Multiply the first term in each set of brackets F: x^2 Outer - Multiply the outer term in each set of brackets O: x^2 + 2x Inner - Multiply the inner term in each set of brackets I: x^2 + 2x + 3x Last - Multiply the last term in each set of brackets L: x^2 + 2x + 3x + 6 Finally, simplify: x^2 + 5x + 6 make sure you always leave your answer in the form ax^2 + bx + c remember: (a+b)^2 = a^2 + 2ab + b^2 \qquad not a^2 + b^2 This page uses jsMath. Note that you can get a better display of the maths by downloading special TeX fonts from jsMath. In the meantime, we will do the best we can with the fonts you have, but it may not be pretty and some equations may not be rendered correctly.