What is the integral of (7x^3)/(sqrt(7+x^2)) ?

The integral of (7x^3)/(sqrt(7+x^2)) is 7(1/3 (7+x^2)^{3/2}-7sqrt(7+x^2))+C

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integral of (7x^3)/(sqrt(7+x^2))

\int \frac{7 x ^{3}}{7 + x ^{2}} d x

7 (\frac{1}{3} (7 + x^{2})^{\frac{3}{2}} - 7 7 + x^{2}) + C

Solution steps

\int \frac{7 x ^{3}}{7 + x ^{2}} d x

Take the constant out:

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

= 7 \cdot \int \frac{x ^{3}}{7 + x ^{2}} d x

Apply u-substitution

: \int u^{2} - 7 d u

= 7 \cdot \int u^{2} - 7 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

= 7 (\int u^{2} d u - \int 7 d u)

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

\int 7 d u = 7 u

= 7 (\frac{u ^{3}}{3} - 7 u)

Substitute back

u = 7 + x^{2}

= 7 (\frac{( 7 + x ^{2} ) ^{3}}{3} - 7 7 + x^{2})

Simplify

7 (\frac{( 7 + x ^{2} ) ^{3}}{3} - 7 7 + x^{2}) : 7 (\frac{1}{3} (7 + x^{2})^{\frac{3}{2}} - 7 7 + x^{2})

= 7 (\frac{1}{3} (7 + x^{2})^{\frac{3}{2}} - 7 7 + x^{2})

Add a constant to the solution

= 7 (\frac{1}{3} (7 + x^{2})^{\frac{3}{2}} - 7 7 + x^{2}) + C

\frac{d}{d x} (x^{3} + x^{2} + 1)

\frac{d}{d x} (\frac{x}{1 + 5 x ^{2}})

(t - 1)^{2} y^{^{'}} + 3 (t - 1) y = t + 2

x \to 0 lim (\frac{1 - ln ( x )}{e ^{\frac{1}{x}}})

What is the integral of (7x^3)/(sqrt(7+x^2)) ?
The integral of (7x^3)/(sqrt(7+x^2)) is 7(1/3 (7+x^2)^{3/2}-7sqrt(7+x^2))+C