Edexcel IGCSE Maths 复习笔记 3.2.3 Inverse Functions

Edexcel IGCSE Maths 复习笔记 3.2.3 Inverse Functions

What is an inverse function?

  • An inverse function does the exact opposite of the function it came from
  • Eg. if the function “doubles the number and adds 1”then its inverse will “subtract 1 and halve the result”
  • It is the INVERSE operations in the reverse order

What do inverse functions look like?

  • An inverse function f-1 can be written as:f-1(x) = … or f-1 : x ↦ …
  • Eg. if f(x) = 2x + 1 its inverse can be written as:f-1(x) = x – 1 / 2   or   f-1: x ↦ x – 1 / 2

What do you find an inverse function?

  1. Write the function in the form y=…
  2. SWAP the xs and ys to get x=…
  3. REARRANGE to give y=… again
  4. Write as f-1(x) = … (or f-1 : x ↦ …)
  • Eg. if f(x)=2x+1 its inverse can be found as follows …y= 2x + 1 1   –   1. Write the function as y=…x = 2y + 1 2  –   2. Swap the xs and ysx – 1= 2y 3   –   3. Rearrange into the form y=… (or …=y)

    x – 1 / 2 = yf-1(x) = x – 1 / 2  – 4. Write as f-1(x)=…

Worked Example

Inverse-Functions-Example

转载自savemyexam

更多IGCSE课程
翰林国际教育资讯二维码