I can't get this slope stuff. I'm trying to find the equation for a line. It has a slope of 1/2 and passes through (8,3). Using the equation y=mx+b, I know that it should be y=1/2x+b so y=1/2(8)+b. Now, I don't know what to do. Is the 3 in the b or y spot? It says y=____ I'm so confused...thanks for help.

Question

I can't get this slope stuff. I'm trying to find the equation for a line.  It has a  slope of 1/2 and passes through (8,3).  Using the equation y=mx+b, I know that it should be y=1/2x+b so y=1/2(8)+b.  Now, I don't know what to do.  Is the 3 in the b or y spot? It says y=____ I'm so confused...thanks for help.

drwls · Answer

You are correct that y = (x/2) + b
Since y = 3 at x = 8, you also know that
3 = (8/2) + b = 4 + b.
Therefore b = -1.

y = (x/2) -1

(To answer your question, the 3 goes in the "y" spot when using the (8,3) point and the equation to compute b.)