To simplify the expression \((7x^5)(9x^3)\), you can follow these steps:
- Multiply the coefficients (numbers) together.
- Use the property of exponents to multiply the \(x\) terms.
Step 1: Multiply the coefficients: \[ 7 \times 9 = 63 \]
Step 2: Multiply the \(x\) terms by adding the exponents: \[ x^5 \times x^3 = x^{5+3} = x^8 \]
Putting it all together: \[ (7x^5)(9x^3) = 63x^8 \]
Thus, the simplified expression is: \[ \boxed{63x^8} \]