pentV 2x²+3x-5≥0
 D=9-4*2*(-5)=49
  x=(-3+7)/4=1   x=(-3-7)/4=-2.5
    
                             -2.5                                  1
                 =======o------------------------------o=========>
                                       x∈(-∞;-2.5]∪[1;+∞)

4x²-12x+9≥0
 D=(-12)²-4*4*9=0
  x=12/8=1.5
                                                 1.5
                                 ========o============>
                                    x∈(-∞;+∞)