I will solve both:
first example:
x^2 = 13/(2x - 10) multiply both sides by (2x - 10) to get rid of the denominator
x^2 (2x - 10) = 13
x^2 (2x - 10) - 13 = 0
2x^3 - 10x^2 -13 = 0 I do not see an easy way to factor this...
Second example:
x^2 = 13/2x - 10 multiply both sides by 2x
2x^3 = 13 -20x
2x^3 + 20x - 13 = 0