The equation of the tangent, to the curve $y=x^2-2x-3$ which is perpendicular to the line $x+2y+3=0$, is
Answer & explanation
Correct answer: option 2
Line → $x+2y+3=0$
differentiating w.r.t x to find slope
$\frac{2dy}{dx}+1=0$ ⇒ slope $m$ = $\frac{dy}{dx}=\frac{-1}{2}$
slope tangent is n(tangent ⊥ line)
$⇒mn=-1⇒n×\frac{-1}{2}=-1$
$n=2$ ⇒ slope of tangent
curve → $y=x^2-2x-3$ ...(1)
$\frac{dy}{dx}=2x-2$ so $\frac{dy}{dx}=2⇒x=2$
from (1) when $x=2$
$y=-3$
at (2, -3) slope of tangent is 2
so equation of tangent: $(y-y_0)$ = slope $(x-x_0)$
$⇒y+3=2(x-2)$
$y+3=2x-4$
$2x-y=7$