Simplify 8xy(x^3y)

$8 x y (x^{3} y)$

Multiply $x$ by $x^{3}$ by adding the exponents.

Move $x^{3}$ .

$8 (x^{3} x) y \cdot y$

Multiply $x^{3}$ by $x$ .

Raise $x$ to the power of $1$ .

$8 (x^{3} x^{1}) y \cdot y$

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$8 x^{3 + 1} y \cdot y$

Add $3$ and $1$ .

$8 x^{4} y \cdot y$

Multiply $y$ by $y$ by adding the exponents.

Move $y$ .

$8 x^{4} (y \cdot y)$

Multiply $y$ by $y$ .

$8 x^{4} y^{2}$