Skin tags that have changed color or bleed may require your doctor's evaluation and reassurance. Rarely, thrombosed skin tags may be a sign of another condition and need to be biopsied.
The x-axis and y-axis are two lines that create the coordinate plane. The x-axis is a horizontal line and the y-axis is a vertical line. I'm sure you've heard that a million times, but it might hard for you to remember which one is which. Here is a little trick to help you remember...
Since a horizontal line never moves up or down, its y-coordinates never change. That means the change in y-coordinates is 0. When we divide by the change in x-coordinates to find slope, our final answer will be 0. Vertical lines go straight up and down. Here is a picture of a vertical line.