determine the x-coordinate of the point on the curve y=2x(lnx) at which the tangent line is parallel to the line y=4x+9
slope must be 4
y = 2 x ln x
slope = dy/dx = 4 = 2x(1/x) + 2 ln x
4 = 2 +2 ln x
2 = 2 ln x
ln x = 1
e^lnx = x = e^1
x = e