x^2-20=x( x to the second power minus 20 equals)?

x^2 - 20 = x or x^2 - x - 20 = 0 can be solved by factoring the left side.

(x -5)(x+4) = 0 implies that x = 5, -4 are the solutions.

x^2 - 20 = x
x^2 - x - 20 = 0
x^2 + 4x - 5x - 20 = 0
(x^2 + 4x) - (5x + 20) = 0
x(x + 4) - 5(x + 4) = 0
(x + 4)(x - 5) = 0

x + 4 = 0
x = -4

x - 5 = 0
x = 5

∴ x = -4, 5

Is your problem x^2 - 20 = x? If so, then subtract x from both sides to get:

x^2 - x - 20 = 0. Factor. Find two numbers that when multiplied together = - 20 and when added equals - 1, the implied number in front of the middle term, x.

Try - 5 and + 4.

(x - 5)(x + 4) = 0. Set each binomial = 0 and solve for x.

x - 5 = 0. x = 5.

x + 4 = 0. x = - 4.

Answer: x = 5, x = 4

Either x^2 - 20 = 0 or x = 1 So x = rt20 or -rt20 or 1.
[I assume you typed the problem correct]

(x+sqr(20))(x-sqr(20)) you should simplify further