Atriangle's area is given by the expression 3x2-x+12. the height is 6x. the base off the triangle is the quotient of the area and 1/2 of the height. which expression represents the base of the triangle?

x/2-1/6+4/x
x-1/3+4x
x/2-1/6+4x
x-1/3+4/x