Question

lf the line $ax+by+c=0$ is a normal to the curve $xy=1$, then :

• A. $a>0,b>0$
• B. $a>0,b<0$
• C. $a<0,b>0$
• D. $a<0,b<0$

Answer 1

Answer: (B), (C)

$a>0,b<0$
$a<0,b>0$

$x{t}^3-yt-t^4+120$
$e{q}^n$ of the normal at $t$ will same as the line $ax+by+c=0$
$\therefore \frac{t^3}{a}=\frac{-t}{b}=\frac{-1-t^4}{c}$
$t^2=\frac{-a}{b}$
$\therefore ab<0$