# how to prove $a+b-ab \le 1$ if $a,b \in$?

Given:

$0 \le a \le 1$

$0 \le b \le 1$

Prove: $a + b – ab \le 1$

#### Solutions Collecting From Web of "how to prove $a+b-ab \le 1$ if $a,b \in$?"

Hint: in that interval,
$$(1-a)(1-b) \ge 0$$

$$ab-a-b+1=(a-1)(b-1)\ge 0$$ since $a-1\le0$ and $b-1\le 0$.