Question

Factor 25x2 – 16.

Answer 1

Answer:

D. (5x + 4)(5x – 4)

Step-by-step explanation:

This is the difference of two squares

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

Following from above,

25$25x^{2} -16$

Taking the elements of the expression

$25x^{2} = 5^{2}x^{2}$

Using the law of indices,

$a^{2} b^{2} = (ab)^{2}$

$25x^{2} = (5x)^{2}$

$16 = 4^{2}$

Therefore,

$25x^{2} -16$ =  $(5x)^{2} - 4^{2}$

=$(5x-4)(5x+4)$

Hence the correct answer is Option D.

Answer 2

The answer is D. (5x+4) (5x-4)

What I did was multiply. So the first step I did was take 5x and mutiplied it by 5x which gave me 25x2. Then after that I took 5x and muliplied it by -4 which gave me -20x. 

The second step was taking 4 and multiplied it by 5x which would be +20x and then 4 x -4 would be -16 so when you write it down your problem is gonna be like this: 25x2 - 20x +20x -16

Last step! is to cross out both 20x's cause it's going to be 0 but the thing is you do not put the 0 in just leave it blank so your answer is 25x2 - 16. Hope this helps! :)

~Shadow