How can I find the equation of the tangent line at x=4 for y=2x?

[fishingspree2]

We know that the slope of the tangent line at a point on a curve is found by evaluating the derivative of the curve at that point.

Say we have the curve y=2x.
Say I wanted to find the tangent line at x=4
dy/dx=2
The first derivative is a constant, which is not surprising since the curve is always changing at the same rate.
However, since the first derivative is a constant, how can I find the equation of the tangent line at x=4? We can't say it's y=2 since that line does not intersect y=2x at x=4.

Can anyone help me

 

[Integral]

The tangent to a line is the line itself.

 

[fishingspree2]

Ohhh I forgot you needed to multipliy the slope by x. Thank you very much