Question

Harsha thought of a number. She added $13$ to the number then multiplied the result by $4$ .

a)Write this as a function as a mapping.Harsha's answer was $6$

b)Use inverse functions to work out the number Harsha thought of. Show all your working: ?

Answer 1

(a) Le the number she thought be $x$

$(x+18)4=y$

(b) inverse function $\Rightarrow$ $x=\frac{y}{4}-13$

now exchanging $x$ and $y$ will give us inverse function in standard format

$y=\frac{x}{4}-13$

here $x=6$

$y=\frac{6}{4}-13=\frac{-23}{2}$