Question

What is the product of (4x – 7)(4x + 7)?

A. 16x2 + 56x – 49
B. 8x2 + 56x – 49
C. 8x2 – 49
D. 16x2 – 49

Answer 1

`(4x - 7)(4x + 7)`
As you might've noticed that, it's in the form of
(a+b) (a-b)
where
a = 4x and b = 7


Now wherever an expression is in this form we use an alzebric identity to solve it. whichis as followed,

`(a + b)(a - b) = {a}^(2) - {b}^(2)`

Simply use that identity and we'll get


`{(4x)}^(2) - {7}^(2) \\ = 16 {x}^(2) - 49 \\`



Therefore option (D) is the correct answer.





Hope you got it.

Answer 2

Multiply using FOIL method (first, outside, inside, last)

=(4x – 7)(4x + 7)
=(4x * 4x) + (4x * 7) + (-7 * 4x) + (-7 * 7)
=16x^2 + 28x - 28x - 49
x term cancels out to zero
=16x^2 - 49

ANSWER: D) 16x^2 - 49

Hope this helps! :)