What is the integral of (11x^3)/(sqrt(9+x^2)) ?

The integral of (11x^3)/(sqrt(9+x^2)) is 11(1/3 (9+x^2)^{3/2}-9sqrt(9+x^2))+C

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integral of (11x^3)/(sqrt(9+x^2))

\int \frac{11 x ^{3}}{9 + x ^{2}} d x

11 (\frac{1}{3} (9 + x^{2})^{\frac{3}{2}} - 9 9 + x^{2}) + C

Solution steps

\int \frac{11 x ^{3}}{9 + x ^{2}} d x

Take the constant out:

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

= 11 \cdot \int \frac{x ^{3}}{9 + x ^{2}} d x

Apply u-substitution

= 11 \cdot \int u^{2} - 9 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

= 11 (\int u^{2} d u - \int 9 d u)

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

\int 9 d u = 9 u

= 11 (\frac{u ^{3}}{3} - 9 u)

Substitute back

u = 9 + x^{2}

= 11 (\frac{( 9 + x ^{2} ) ^{3}}{3} - 9 9 + x^{2})

Simplify

11 (\frac{( 9 + x ^{2} ) ^{3}}{3} - 9 9 + x^{2}) : 11 (\frac{1}{3} (9 + x^{2})^{\frac{3}{2}} - 9 9 + x^{2})

= 11 (\frac{1}{3} (9 + x^{2})^{\frac{3}{2}} - 9 9 + x^{2})

Add a constant to the solution

= 11 (\frac{1}{3} (9 + x^{2})^{\frac{3}{2}} - 9 9 + x^{2}) + C

What is the integral of (11x^3)/(sqrt(9+x^2)) ?
The integral of (11x^3)/(sqrt(9+x^2)) is 11(1/3 (9+x^2)^{3/2}-9sqrt(9+x^2))+C