Question

The number of tangents drawn to the curve $xy=4$ from point $(0,1)$ is

• A. 0
• B. 1
• C. 2
• D. Infinite

Answer 1

Answer: (B)

Equation of tangent is $y-4/h=-4/h^2(x-h)$
It passes through $(0,1)\Rightarrow 1-4/h=4h/h^2$
$\Rightarrow h-4=4\Rightarrow h=8$
$\Rightarrow$ tangent is $y-1/2=-1/16(x-8)$.