Real Functions

Pure Mathematics — Second Secondary

Real Functions

Common mistakes

Key points

Forgetting to remove the zeros of the denominatorwhen finding the domain of a rational function, exclude every value that makes the denominator zero.

Confusing the domain with the rangethe domain contains the x-values, while the range contains the output values f(x).

Reversing the inequality incorrectlydividing both sides by a negative number reverses the sign, so −2x ≥ 6 gives x ≤ −3.

Using the wrong brackets in an intervalan included end value uses a square bracket, while an excluded value always uses a round bracket.

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