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

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

2 Answers

4 votes


(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.
User Pooran
by
8.2k points
1 vote
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! :)
User Nikita Zhuikov
by
8.4k points