Question

Решите ур-е
x^2 - 21=4x

Answer 1

x^2-4x-21=0
D=-b-4ac=-(-4)^2-4*1*(-21))=16+84=100
x1=(4+10)/2=7
x2=(4-10)/2=-3

Answer 2

x^2-4x-21=0
D=16-4*(-21)*1=100
x1=4+10/2=7
x2=4-10/2=-3