1) решите 6х^2=5х+1 2) найти сумму корней х^2-3х+7х=77

6х^2=5х+1
6x^2 - 5x - 1 = 0
D =  25 - 4*6*(-1) = 25 + 24 - 49 = 7^2
x = 5+7 / 2*6 = 12 / 12 = 1
x = 5-7 / 2*6 = -2 / 12 = -1/6


Х^2-3х+7х=77
x^2 + 4x - 77 = 0
D = 4^2 - 4*1*(-77) = 16 + 308 = 324 = 18^2
x = -4 +18 / 2 = 14/2 = 7
x = -4 - 18 / 2 = -22/2 = - 11

сумму корней  7 + (-11) = -4