The value of $c$ such that the straight line joining the points $(0,3)$ and $(5,-2)$ is tangent to the curve $y=\frac{c}{x+1}$ is

If the percentage error in the radius of circle is 3 , then the percentage error in its area is

The equation of the tangent to the curve $y=x^3-2 x+7$ at the point $(1,6)$ is

The distance ( s ) travelled by a particle in time $t$ is given by $S=4 t^2+2 t+3$. The velocity of the particle, when $t=3 \mathrm{sec}$ is