Question

Given that
f(n) = n^2 - 4n + 3
& g(n) = 2n - 1
find gf(-2)

Answer 1

The value of
`gf\left(-2\right)` will be:

• 
  `gf\left(-2\right)=29`

Explanation:

Given the functions

`f(n) = n^2 - 4n + 3`

`g\left(n\right)\:=\:2n\:-\:1`

`f\left(-2\right)\:=\:\left(-2\right)^2\:-\:4\left(-2\right)\:+\:3`

`=\left(-2\right)^2+4\cdot \:2+3`

`=2^2+4\cdot \:2+3`

`=2^2+8+3`

`=4+11`

`=15`

so

`gf\left(-2\right)=g\left(15\right)`

`=2n-1=2\left(15\right)-1=30-1=29`

Therefore,

• 
  `gf\left(-2\right)=29`