Question

1) Define onto function. 2) Find k if f.f(k) = 5 where f (k) = 2k – 1​

Answer 1

3

Explanation:

2k-1=5

>2k=5+1=6

>k=3

Answer 2

1)

An onto function is a function where it's range is the term in that function.

`{ \sf{if \: function \: is \: x \: to \: y}} \\ { \sf{then \: range \: of \: function \: is \: y}} \\ i.e \: \: f(x) = y`

It is given by formula:

`{ \boxed{ \sf{ {x}^(y) - {}^(x) c _(1)(n - 1) {}^(y) + {}^(x) c _(2) (x - 2) {}^(y) + ..... {x}^(n) }}}`

2).

`f(k) = 2k - 1 \\ but \: f(k) = 5 \\ 2k - 1 = 5 \\ 2k = 1 + 5 \\ 2k = 6 \\ k = 3`