Question

a) Prove that a strictly increasing function from R to itself is one-to-one.

b) Give an example of an increasing function from R to itself is not one-to-one.

Short answer

f(x) = 0 for x > 0 and f (x) = x for$x\le 0$

Step-by-step solution

Step: 1

Let f be the given strictly increasing function from R to itself.

If a < b , then f(a) > f(b) if then f(a) < f(b)

Thus if $a\ne b$, then$f\left(a\right)\ne f\left(b\right)$

Step: 2

Therefore,

$f\left(x\right)=0\text{for}x>0\text{and}f\left(x\right)=x\text{for}x\le 0$