Question

Which is a factor of 144 − 49x2?

12 - 7x2
72 – 7x2
12 – 7x
72 + 7x

Answer 1

Answer is C

Explanation:

Answer 2

(12-7x)

Explanation:

144 − 49x²

by observation, we can see that 144 = 12² and 49 = 7²

hence we can rewrite the equation

144 − 49x²

= 12² - 7²x²

= 12² - (7x)²

recall that the expression x² - y² = (x+y)(x-y)

hence,

12² - (7x)²

= (12 + 7x)(12-7x)

(12-7x) appears in the expression above, hence 12 -7x is a factor