To factor the expression \( 72p + 81 \), we can start by finding the greatest common factor (GCF) of the coefficients 72 and 81.
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Find the GCF:
- The prime factorization of \( 72 \) is \( 2^3 \times 3^2 \).
- The prime factorization of \( 81 \) is \( 3^4 \).
- The common factor is determined by the lowest powers of the common prime factors.
- The common prime factor is \( 3 \), and the lowest power is \( 3^2 \), which is \( 9 \).
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Factor out the GCF:
- Now we factor \( 9 \) out of the expression: \[ 72p + 81 = 9(8p + 9) \]
Thus, the factored form of \( 72p + 81 \) is \( 9(8p + 9) \).
The answer is \( 9(8p + 9) \).