(9x-4)^2-(x-13)^2=0 нужны корни уравнения

(9x - 4)^2 - (x - 13)^2 = 0
81x^2 - 72x + 16 - (x^2 - 26x + 169) = 0
81x^2 - 72x + 16 - x^2 + 26x - 169 = 0
80x^2 - 46x - 153 =0
D = b^2 - 4ac = 2116 + 48960 = 51076 = 226^2
x1= ( 46 + 226) / 160 = 17
x2 = ( 46 - 226) / 160 = - 1,125