Question 10: Find the integration using Substitution Method. (3 marks) \[ \int x\left(3 x^{2}+5\right)^{3} d x \]

Step 1 ：Let \(u = 3x^2 + 5\), then \(du = 6xdx\)

Step 2 ：Substitute in the given integral: \(\int\frac{1}{6}u^3du\)

Step 3 ：Evaluate the integral: \(\frac{1}{6}\left(\frac{1}{4}u^4+C\right)\)