The answer is A.
When multiplying binomials, a useful way of remembering is the FOIL method (first*first, outside*outside, inside*inside, last*last).
We can find the correct answer by working backwards, which is basically just like finding the square root of each term in this expression.
For [tex]25x^2[/tex] we have to find the square: [tex]\sqrt{25x^2}[/tex]. The square root symbol and the exponent 2 basically cancel each other out, and the square root of 25 is 5.
Let's use the same method for [tex]-9y^2[/tex]. [tex]\sqrt{-9y^2} --> \sqrt{-9y} = 3y[/tex]. In this case, though, it will be written as -3y.
Now for [tex]z^2[/tex]: [tex]\sqrt{z^2} = z[/tex]
So the answer is [tex]5x - 3yz[/tex].
