Simplify (15a^3)(-3a)

$(15 a^{3}) (- 3 a)$

Step 1

Rewrite using the commutative property of multiplication.

$15 \cdot - 3 a^{3} a$

Step 2

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

Move $a$ .

$15 \cdot - 3 (a \cdot a^{3})$

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

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

$15 \cdot - 3 (a^{1} a^{3})$

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

$15 \cdot - 3 a^{1 + 3}$

Add $1$ and $3$ .

$15 \cdot - 3 a^{4}$

Step 3

Multiply $15$ by $- 3$ .

$- 45 a^{4}$