A)
x²-2x-8<0<br>x²-2x-8=0
D=4+32=36
x₁=(2-6)/2= -2
x₂=(2+6)/2=4
+ - +
------ -2 ----------- 4 ---------
\\\\\\\\\\\\\\
x∈(-2; 4)
б)
5x²-11x+6≥0
5x²-11x+6=0
D=121-120=1
x₁=(11-1)/10=1
x₂=(11+1)/10=1.2
+ - +
------- 1 ----------------- 1.2 ------------------
\\\\\\\\ \\\\\\\\\\\\\\\\\\\\
x∈(-∞; 1]U[1.2; +∞)
в)
x²-2x>0
x(x-2)>0
x=0 x=2
+ - +
-------- 0 ------------- 2 -------------
\\\\\\\\\ \\\\\\\\\\\\\\\\
x∈(-∞; 0)U(2; +∞)