(2-7x)(5+4x)=0 решите уравнение

2-7х=0                               5+4х=0

-7х=-2                                4х=-5

х=2\7                                 х=- 5\4 або 1 1\4

(2-7x)(5+4x)=010+8x-35x-28x^2=0-28x^2-27+10=0D = 729-4*(-28)*10 = 729+1120 = 1849x1= 27-43 / -56  = -16/-56 = 16/56 = 8/28 / =4/14 / 2/7x2 = 27+43 / -56 = 70/-56 = -5/4 = -1.25или 2-7x = 0-7x = -2x = 2/75+4x = 04x =-5x = -5/4x= -1.25