$\int{ {x}^{2} } \mathrm{d} x+\int{ {\cos\left({x}\right)}^{3} } \mathrm{d} x+\int{ 3 } \mathrm{d} x$
Use $\begin{array} { l }\int{ {x}^{n} } \mathrm{d} x=\frac{ {x}^{n+1} }{ n+1 },& n≠-1\end{array}$ to evaluate the integral$\frac{ {x}^{3} }{ 3 }+\int{ {\cos\left({x}\right)}^{3} } \mathrm{d} x+\int{ 3 } \mathrm{d} x$
Evaluate the indefinite integral$\frac{ {x}^{3} }{ 3 }+\sin\left({x}\right)-\frac{ {\sin\left({x}\right)}^{3} }{ 3 }+\int{ 3 } \mathrm{d} x$
Use $\int{ a } \mathrm{d} x=a \times x$ to evaluate the integral$\frac{ {x}^{3} }{ 3 }+\sin\left({x}\right)-\frac{ {\sin\left({x}\right)}^{3} }{ 3 }+3x$
Simplify the expression$\frac{ {x}^{3}-{\sin\left({x}\right)}^{3} }{ 3 }+\sin\left({x}\right)+3x$
Add the constant of integration $C \in ℝ$$\begin{array} { l }\frac{ {x}^{3}-{\sin\left({x}\right)}^{3} }{ 3 }+\sin\left({x}\right)+3x+C,& C \in ℝ\end{array}$