What is the integral of 3xsqrt(x+3) ?

The integral of 3xsqrt(x+3) is 3(2/5 (x+3)^{5/2}-2(x+3)^{3/2})+C

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integral of 3xsqrt(x+3)

\int 3 x x + 3 d x

3 (\frac{2}{5} (x + 3)^{\frac{5}{2}} - 2 (x + 3)^{\frac{3}{2}}) + C

Solution steps

\int 3 x x + 3 d x

Take the constant out:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= 3 \cdot \int x x + 3 d x

Apply u-substitution

= 3 \cdot \int (u - 3) u d u

Expand

(u - 3) u : u^{\frac{3}{2}} - 3 u

= 3 \cdot \int u^{\frac{3}{2}} - 3 u d u

Apply the Sum Rule:

\int f (x) \pm g (x) d x = \int f (x) d x \pm \int g (x) d x

= 3 (\int u^{\frac{3}{2}} d u - \int 3 u d u)

\int u^{\frac{3}{2}} d u = \frac{2}{5} u^{\frac{5}{2}}

\int 3 u d u = 2 u^{\frac{3}{2}}

= 3 (\frac{2}{5} u^{\frac{5}{2}} - 2 u^{\frac{3}{2}})

Substitute back

u = x + 3

= 3 (\frac{2}{5} (x + 3)^{\frac{5}{2}} - 2 (x + 3)^{\frac{3}{2}})

Add a constant to the solution

= 3 (\frac{2}{5} (x + 3)^{\frac{5}{2}} - 2 (x + 3)^{\frac{3}{2}}) + C

What is the integral of 3xsqrt(x+3) ?
The integral of 3xsqrt(x+3) is 3(2/5 (x+3)^{5/2}-2(x+3)^{3/2})+C