Answer:
(3x + 7)(3x - 7)
Step-by-step explanation:
9x² - 49 ← is a difference of squares and factors in general as
a² - b² = (a + b)(a - b) , then
9x² - 49
= (3x)² - 7²
This is where the error has been made in that 9x has been used instead of 3x
= (3x + 7)(3x - 7) ← in factored form
