Functions: evaluating, solving and composite
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The teaching part (1 min) is free to watch. A free account opens the whole lecture: 8 practice questions, 1 real past-paper question with the answer explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- A machine with a rule
- Function notation
Read the transcript of the teaching part
Last time
Before we start: last time, in Functions, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
A machine with a rule
Think of a machine. You put a number in, it follows a rule, and a number comes out. A function is exactly that. Call this machine f, with the rule double and add five. Put in three and out comes eleven. Today you will use these machines, run two of them one after the other, and run one backwards.
Function notation
We write f of x equals two x plus five. This is the rule. The letter x stands for whatever number goes in. f of three means: replace every x with three. Two times three is six, plus five is eleven. f of minus one: put the minus number in brackets. Two times minus one is minus two. Plus five gives three.
How often it comes up
How often Cambridge has asked each part, counted by ExamYard from every past paper in its question bank: Composite functions · Evaluating and solving with functions.
The whole chapter: Functions.
Chapter 17: Functions
- Functions: evaluating, solving and composite 6 min
Also for IGCSE Maths 0580
Which topics come up most in IGCSE Maths 0580 past papers, counted from every paper since 2004.