\left(u v\right)' = u' \, v + u \, v'; uv′ = u′v + uv′;
u \, v' = \left(u v\right)' - u' \, v;uv′ = uv′− u′v;
\int u \, v' \,\mathrm{d}x = \int \left(u v\right)' \mathrm{d}x - \int u' \, v \,\mathrm{d}x = u v + C - \int u' \, v \,\mathrm{d}x;∫ uv′dx = ∫ uv′dx −∫ u′vdx = uv + C −∫ u′vdx;