146. $\int(2 x+3)^{4} d x$.

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146. $\int(2 x+3)^{4} d x$.
Solved. $\int(2 x+3)^{4} d x=\left|\begin{array}{l}z=2 x+3 \\ d z=2 d x \\ d x=\frac{1}{2} d z\end{array}\right|=\frac{1}{2} \int z^{4} d z=0.1 z^{5}+C=$ $=0.1(2 x+3)^{5}+C$.

Verification: $\quad d\left(0.1(2 x+3)^{5}+C\right)=0.5(2 x+3)^{4}(2 x)^{\prime} d x=(2 x+3)^{4} d x$.