If you mean 5x^2 -125 then it is 5(x^2 -25) when factored
5x2
6x: the co-efficient of x is 6. This should be enough to explain the term.
(5x-6)(x-3)
(5x - 1)(x + 6)
To factor any term, divide by the LCF (largest common factor) of the term. For 5x2-45, the LCF is 5. 5x2-45 = 5(x2-9) It can, of course, be factored even further to become: 5(x2-9) = 45(x2/9 - 1) but when factoring, we usually don't need to go past 5(x2-9) (for example, you've figured out that x2 = 9, thus x = +/- 3.)
I'm pretty sure you didn't write down the expression to be factored correctly. If you can't do that, neither you nor anybody else will be able to factor your expression.
5x2 + 3x - 1 does not have rational factors.
5(x2 - 25) 5(x + 5)(x - 5)
5x2-46x+9 = (5x-1)(x-9)
5x2 + 20x = 5x (x + 4)
The expression has no rational factors.
5x2-18x+9 = (5x-3)(x-3)
x(5x - 4)
With great difficulty!
5x2
5x2 + x - 6 = (5x + 6)(x - 1) 5x2 - x - 6 = (5x - 6)(x + 1)
The GCF is 5x2