Question:
The point on the curve $y=x^{2}-3 x+2$ where tangent is perpendicular to $y=x$ is
A. $(0,2)$
B. $(1,0)$
C. $(-1,6)$
D. $(2,-2)$
Solution:
Given that the curve $y=x^{2}-3 x+2$ where tangent is perpendicular to $y=x$
Differentiating both w.r.t. $\mathrm{x}$,
$\frac{\mathrm{dy}}{\mathrm{dx}}=1$ and $\frac{\mathrm{dy}}{\mathrm{dx}}=2 \mathrm{x}-3$
$\because$ the point lies on the curve and line both
Slope of the tangent $=-1$
$\Rightarrow 2 x-3=-1$
$\Rightarrow x=1$
And $y=1-3+2$
$\Rightarrow y=0$
So, the required point is $(1,0)$.