Isnt it suppose to be x=5 because -25 and +5 is equals to -20 but we are finding 20 not -20 thus isnt it suppose to be +25 and -5 hence
X+25=0 x-5=0
X=-25 X=5
(Rej)

Answer : X=5
Im not sure but i think it is like that??

Hii,

Nope, it does not work that way. Our equation to obtain is

x2 - 20x - 125 = 0

and this factorises to

(x - 25) (x + 5) = 0
x - 25 = 0 or x + 5 = 0
x = 25 or x = -5

You can always sub back these values into your starting equation to ensure their validities.

Then, we reject the negative solution for this question since lengths are positive.

The derived equation is x squared - 20x - 125 =0
So we are actually looking for -20x
Hope this clarifies:)

Ohh i understand now thank you