Question

The coefficient of $y$ in $(y^2+\frac{c}{y}{)}^5$ is

• A. $20c$
• B. $10c$
• C. $10c^3$
• D. $20c^2$

Answer 1

The correct option is C $10c^3$

The general term is
$t_r{=}^5{C}_r.(y^2{)}^r.(\frac{c}{y}{)}^{5-r}$
If the power of $y$ in above general term should be $1$, we have,
$2r-(5-r)=1$ which gives $r=2$.
Putting this value of $r$ in the general term expression, we get the coefficient of $y$