Functions

Question 1

Regular functions

Answer 1

Substitute number into function
Put substitute value into where x is in function
Be careful with negatives

Question 2

Inverse functions

Answer 2

1. write as y=
2. swap xs and ys
3. rearrange to make y subject
4. write answer as f^-1 (x) = ……

Question 3

Composite functions

Answer 3

1. put number in bracket into second function
2. then put answer into first function
   If x is in bracket, rewrite first function with second function wherever there is an x

Question 4

Domain of a function

Answer 4

the set of all the values that can be put into the function

doma[in] - numbers that can go in

may be written as an inequality, so range will likely be an inequality too - useful to draw graph to help

Question 5

Range of a function

Answer 5

the collection of values that can ‘come out of’ the function

Question 6

Range of an inverse function

Answer 6

Same as the domain of the original function

Question 7

Excluded values - 2 rules

Answer 7

1. can’t divide a fraction by 0

2. can’t have a negative square root