Question

2х2-11х-21=0 Решите ПЖ

Answer 1

2х^2-11х-21=0
a=2 b= -11 c= -21
D=b^2 -4ac= 11^2 - 4*2*(-21) = 121 + 168= 289= 17^2 > 0 (2k)
x1= -b +D = 11 + 17 = 28 = 7
2a 2*2 4

x2= -b-D = 11-17 = -6 = -1,5
2a 2*2 4