6х²-5|x|-1=0

x>0

6х²-5x-1=0

D= 25+24=49

x₁=(5+7)/12=1

x₂=(5-7)/12= -1/6 < 0

x<0

6х²+5x -1=0

D=49

x₁=(-5+7)/12= 1/6 >0

x₂=(-5-7)/12= -1

Ответ : х=1 ; х= -1

х²+8х -20=0

х²+8х +16- 36=0

(х+4)² - 6²=0

(х+4 - 6)(х+4 +6) = (х-2)(х+10)=0

х-2=0   х= 2

х+10=0 х=-10