To solve this equation, we can first simplify the expression by expanding the binomial in the parentheses raised to the power of -10.

(х^2-6х)^-10 = (x(x-6))^-10

Now, using the property of exponents (a^m * a^n = a^(m+n)), we can rewrite it as:

(x(x-6))^-10 = 1/(x(x-6))^10

So, our equation becomes:

1/(x(x-6))^10 * (x^2-6x) + 21 = 0

Now, we need to find the values of x that satisfy this equation. Let's start by multiplying both sides by (x(x-6))^10 to get rid of the denominator:

x^2 - 6x + 21(x(x-6))^10 = 0

This is a quadratic equation that can be solved by factoring or using the quadratic formula. However, given the complexity of the expression, it might be difficult to do so.

I recommend using a numerical method or a computer algebra system to find the solutions to this equation.