Question

Which equation is true?

9x2 – 25 = (3x – 5)(3x – 5)
9x2 – 25 = (3x – 5)(3x + 5)
9x2 – 25 = –(3x + 5)(3x + 5)
9x2 – 25 = –(3x + 5)(3x – 5)

Answer 1

9x2 – 25 = (3x – 5)(3x + 5)

Answer 2

`(3x-5)(3x+5)` is the right answer.

Explanation:

The given expression is :

`9x^(2) -25`

We can say that it is in the form of
`a^(2)- b^(2)`

`a^(2)` is
`9x^(2)` or a = 3x

`b^(2)` is 25 or b = 5

Now, when we multiply
`(a-b)(a+b)` we get
`a^(2)- b^(2)`

So, putting the values of a and b in
`(a-b)(a+b)` to get the answer.

`(3x-5)(3x+5)`

We can check this by multiplying both,
`9x^(2) +15x-15x-25`

=
`9x^(2) -25`

Therefore, option B is correct.