Решить x во 2-ой степени -2.4x - 13 =0

Question

Решить x во 2-ой степени -2.4x - 13 =0

Answer 1

X^2 - 2.4x - 13 = 0   /*5
5x^2 - 12x - 65 = 0 
D = 144 + 4*65*5 = 1444
√D = 38

x1 = ( 12 + 38)/10 = 50/10 = 5
x2 = (12 - 38)/10 = - 26/10 = - 2,6