# what's the formula?

• March 22nd 2009, 07:23 PM
faolan
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?
• March 22nd 2009, 07:29 PM
Reckoner
Quote:

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 $y$). What must be true about the slopes of two parallel lines? This fact will give you your equation, which you can then solve for $y.$