3x + 6x-4 = 0

3x + 6x-4 = 0

3x^2+6x-4=0
x^2+2x-4/3=0
x^2+2x+1-1-4/3=0
(x+1)^2-7/3=0
(x+1)^2-21/9=0
(x+1-√21/3)(x+1+√21/3)=0
X = √ 21 / 3-1 or x = - √ 21 / 3-1