Payton,
The quickest way to see the answer is using the substitution method:
If we make u = 5x, Why like that?
Well if u = 5x
then u2 = (5x)(5x) = 25x2
and 4u = (4)(5x) = 20x
So plug those into the equation and now it goes from:
Before: 25x2+20x+4
After: u2 +4u+ 4
Now we can easily see get the factors for this equation!
It is (u +2)(u+2) or in the simplest form (u+2)2
But, we need our answer in terms of x, so we replace the 5x for every u we see in the answer:
So (u+2)2
Becomes -> (5x+2)2
There is only one coefficient on the x term and that is 5!
Try multiplying it back out to verify that the equations are indeed the same. They are! Good luck with Algebra!