Question

If points $(a,0),(0,b)$ and $(1,1)$ are collinear, then $\left(\frac{a+b}{ab}\right)$ equals:

• A. $1$
• B. $-1$
• C. $2$
• D. $\sqrt{2}$

Answer 1

The correct option is A $1$

The given points are collinear

$\Rightarrow$ slopes of any two points are equal

$\Rightarrow \frac{b-0}{0-a}=\frac{1-b}{1-0}$

$\Rightarrow b=-a+ab$

$\Rightarrow a+b=ab$

$\Rightarrow \frac{a+b}{ab}=1$