expand. if necessary, combine like terms. (3x + 7)(3x - 7) =
expand. if necessary, combine like terms. (3x + 7)(3x - 7) =
Answer
Answer:
$9x^{2}-49$
Explanation:
Step1: Use FOIL method
$(3x + 7)(3x - 7)=3x\times3x+3x\times(-7)+7\times3x + 7\times(-7)$
Step2: Calculate each product
$3x\times3x = 9x^{2}$, $3x\times(-7)=-21x$, $7\times3x = 21x$, $7\times(-7)=-49$
Step3: Combine like - terms
$9x^{2}-21x + 21x-49=9x^{2}+(-21x + 21x)-49=9x^{2}-49$