What is the integral of x(8x+7)^8 ?

The integral of x(8x+7)^8 is 1/5760 (9(8x+7)^{10}-70(8x+7)^9)+C

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integral of x(8x+7)^8

\int x (8 x + 7)^{8} d x

\frac{1}{5760} (9 (8 x + 7)^{10} - 70 (8 x + 7)^{9}) + C

Solution steps

\int x (8 x + 7)^{8} d x

Apply u-substitution

= \int \frac{u ^{8} ( u - 7 )}{64} d u

Take the constant out:

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

= \frac{1}{64} \cdot \int u^{8} (u - 7) d u

Expand

u^{8} (u - 7) : u^{9} - 7 u^{8}

= \frac{1}{64} \cdot \int u^{9} - 7 u^{8} 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

= \frac{1}{64} (\int u^{9} d u - \int 7 u^{8} d u)

\int u^{9} d u = \frac{u ^{10}}{10}

\int 7 u^{8} d u = \frac{7 u ^{9}}{9}

= \frac{1}{64} (\frac{u ^{10}}{10} - \frac{7 u ^{9}}{9})

Substitute back

u = 8 x + 7

= \frac{1}{64} (\frac{( 8 x + 7 ) ^{10}}{10} - \frac{7 ( 8 x + 7 ) ^{9}}{9})

Simplify

\frac{1}{64} (\frac{( 8 x + 7 ) ^{10}}{10} - \frac{7 ( 8 x + 7 ) ^{9}}{9}) : \frac{1}{5760} (9 (8 x + 7)^{10} - 70 (8 x + 7)^{9})

= \frac{1}{5760} (9 (8 x + 7)^{10} - 70 (8 x + 7)^{9})

Add a constant to the solution

= \frac{1}{5760} (9 (8 x + 7)^{10} - 70 (8 x + 7)^{9}) + C

What is the integral of x(8x+7)^8 ?
The integral of x(8x+7)^8 is 1/5760 (9(8x+7)^{10}-70(8x+7)^9)+C