which is a factor of 144 - 49x²?\n12 - 7x²\n72 - 7x²\n12 - 7x\n72 + 7x

Explanation:

Step1: Recognize difference - of - squares

The expression $144 - 49x^{2}$ is in the form $a^{2}-b^{2}$, where $a = 12$ ($a^{2}=144$) and $b = 7x$ ($b^{2}=49x^{2}$).

Step2: Apply difference - of - squares formula

The difference - of - squares formula is $a^{2}-b^{2}=(a + b)(a - b)$. So, $144 - 49x^{2}=(12 + 7x)(12-7x)$.

Answer:

C. $12 - 7x$