The slope of the tangent to the curve $x=t^{2}+3 t-8, y=2 t^{2}-2 t-5$ at point $(2,-1)$ is
A. $\frac{22}{7}$
B. $\frac{6}{7}$
C. $-6$
D. $\frac{7}{6}$
Given that $x=t^{2}+3 t-8, y=2 t^{2}-2 t-5$
Differentiating both the sides,
$\frac{\mathrm{dx}}{\mathrm{dt}}=2 \mathrm{t}+3, \frac{\mathrm{dy}}{\mathrm{dt}}=4 \mathrm{t}-2$
$\Rightarrow \frac{\mathrm{dy}}{\mathrm{dx}}=\frac{\frac{\mathrm{dy}}{\mathrm{dt}}}{\frac{\mathrm{dx}}{\mathrm{dt}}}$
$\Rightarrow \frac{d y}{d x}=\frac{\frac{d y}{d t}}{\frac{d x}{d t}}$
$=\frac{4 t-2}{2 t+3}$
The given point is $(2,-1)$
$2=t^{2}+3 t-8,-1=2 t^{2}-2 t-5$
On solving we get,
$\mathrm{t}=2$ or $-5$ and $\mathrm{t}=2$ or $-1$
$\because \mathrm{t}=2$ is the common solution
So, $\frac{\mathrm{dy}}{\mathrm{dx}}=\frac{8-2}{4+3}$
$=\frac{6}{7}$