Find the sum of n terms of the series 1.5+3.8+5.11+---------------n

Question

$(a)\;5n^2+6n+10\qquad(b)\;\frac{n(n+1)(2n+1)}{6}\qquad(c)\;\frac{4n^3+7n^2-n}{2}\qquad(d)\;6n^2+9n+1$