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Published byAlison Kelley Modified over 9 years ago
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Algebraic Fractions Algebraic fractions are exactly what their name suggests: fractions with algebra in! Here is an example of an algebraic fraction: Note that this cannot be cancelled! Just as with ordinary fractions, you can multiply, divide, add and subtract algebraic fractions. In fact, the methods are similar. Algebraic fractions crop up a lot in C3 and C4 – today you will look at how to multiply and divide them.
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Algebraic Fractions Multiplying first. Just as with multiplying ordinary fractions, you multiply the tops (numerators) together, then multiply the bottoms (denominators) together. Example: The answer is:
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Algebraic Fractions: Questions
Simplify these, leaving your answers in their lowest forms.
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Algebraic Fractions: Answers
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Leave as factorised as possible!
Algebraic Fractions Sometimes the multiplication can be made easier by cancelling. Example: This looks like it will take a while! Can you do any cancelling before you start multiplying, to make it quicker? Leave as factorised as possible! Yes! 3x + 15 is 3 (x + 5), so you can cancel: 3
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Algebraic Fractions Finally... Example:
Factorise as much as possible to see what to cancel. That gives: Cancelling gives:
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Algebraic Fractions: Questions
Simplify these, giving your answers in their lowest terms.
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Algebraic Fractions: Answers
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Algebraic Fractions Now look at dividing algebraic fractions. Example:
As with ordinary fractions you use a trick to divide. Turn the fraction on the right upside down and multiply instead: Then proceed as before. The answer is:
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Algebraic Fractions Example:
Again find the reciprocal of the fraction on the right and multiply. Can you do any cancelling before the multiplying? Yes!
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Algebraic Fractions: Questions
Simplify these, leaving your answers in their lowest terms.
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Algebraic Fractions: Answers
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Algebraic Fractions: Plenary
From C3 Specimen Paper: Express as a single fraction in its simplest form. Reveal Answer
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