[m]du=(10-3x)`dx[/m]
[m]du=-3dx[/m]
[m]dx=-\frac{1}{3}du[/m]
0 → 10
1 → 10-3*1=7
[m]= ∫^{7} _{10}\frac{(-\frac{1}{3}du)}{\sqrt{u}}=\frac{1}{3}∫^{10} _{7}\frac{du}{\sqrt{u}}=\frac{1}{3}\cdot (2\sqrt{u})|^{10}_{7}=\frac{2}{3}(\sqrt{10}-\sqrt{7})[/m]