Problem $50.$ Calculate the definite integral

${\displaystyle \underset{1}{\overset{5}{}}}(-4x^2)dx$

given that

${\displaystyle \underset{1}{\overset{4}{}}}xdx=7\mathrm{.}5{\displaystyle \underset{1}{\overset{4}{}}}{x}^{2}dx=21{\displaystyle \underset{4}{\overset{5}{}}}{x}^{2}dx=\frac{61}{3}$