Expanding simple quadratics
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When we expand an expression in algebra, we multiply out the brackets. The picture above shows the link between expanding quadratic brackets (sometimes called "double brackets") and areas.
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The important thing when expanding quadratic expressions is to remember to multiply everything in the first bracket by everything in the second bracket. There are some little "tricks" that you can use to help you to do this.
You can use the grid method, based on the method used for normal multiplication. You can use FOIL to remind you to multiply all of the terms. FOIL tells you to:
Or you can use the "smiley face" method - it's just called this because it makes something that looks vaguely like a smiley face. This is really just a more visual version of FOIL, and it just reminds you to multiply all of the terms together. You must also remember to simplify your answer at the end by collecting like terms. Remember that we can't put x² terms with x terms because they represent different things. Normally, you will have to simplify two x terms. |
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