Hello Sir please solve this question :
The coordinates of a moving particle at any time $t$ are given by $ x = \alpha t^3$ and $y = \beta t^3$. The speed of the particle at time $t$ is given by
(a) $t^2 \sqrt {\alpha + \beta}$
(b) $t^3 \sqrt {\alpha^3 + \beta^2}$
(c) $3t^2 \sqrt {\alpha ^2+ \beta^2}$
(d) $3t \sqrt {\alpha ^2+ \beta^2}$
