Question

Which is a factor of 144 - 49x²?
O 12-7x²
O 72-7x²
O 12-7x
O 72 + 7x

Answer 1

Answer: C: 12-7x

Step-by-step explanation:

This expression is a good example of the difference of two squares, as 144 is the square of 12, while 49x² is the square of 7x.

Any difference of two squares $a^2-b^2$ can be factored into the sum of their square roots times the difference of their square roots $(a+b)(a-b)$.

Let's factor our expression.

$144-49x^2=(12+7x)(12-7x)$

Out of all the options given, only $12-7x$ is a factor. Hence, option C is correct.