x = 0
25 x ^ 2 - 10 x = 0
25 * 0 ^ 2 - 10 * 0 = 0
25 * 0 - 10 * 0 = 0
0 - 0 = 0
0 = 0
and
25 x ^ 2 - 10 x = 0 Divide both sides by 5 x
25 x ^ 2 / 5 x - 10 x / 5 x = 0 / 5 x
5 * 5 * x * x / 5 x - 2 * 5 x / 5 x = 0
5 x - 2 = 0 Add 2 to both sides
5 x - 2 + 2 = 0 + 2
5 x = 2 Divide both sides by 5
5 x / 5 = 2 / 5
x = 2 / 5
x = 0 and x = 2 / 5