Thread: what's the formula?

What is the formula for this?


If the line passing through (7,y) and (1,0) is parallel to the line joining 4,4 and -2,1, find y.


How do I solve for y?

Originally Posted by faolan

If the line passing through (7,y) and (1,0) is parallel to the line joining 4,4 and -2,1, find y.

Find the slope of the second line. Find the slope of the first line (in terms of $\displaystyle y$). What must be true about the slopes of two parallel lines? This fact will give you your equation, which you can then solve for $\displaystyle y.$