2*x+4×7*x+4>2*3x×7*3x
2x+4•7x+4>2•3x•7•3x
2x+28x+4>6x•21x
30x+4>126x^2
-126x^2+30x+4=0
D=b-4ac=30-4•(-126•4)=2045
x1,2=
x1=-2/21
x2=1/3