х2+7х-1=0 х2-7х+1=0 х2-15х+56=0

Question

х2+7х-1=0 х2-7х+1=0 х2-15х+56=0

Answer 1

х²+7х-1=0
D=b²-4ac=72-4·1· -1=53
х₁=0,1401
х₂= -7,1401

 

 

х²-7х+1=0
D=b²-4ac= -72-4·1·1=45
х₁=6,8541
х₂=0,1459

 

 

х²-15х+56=0
D=b²-4ac=-152-4·1·56=1
х₁=8
х₂=7