# find slope

• Sep 17th 2008, 08:19 AM
fabxx
find slope
Heyy, i need you guys' help on this too :(

xy coordinate plane graph x=y^2-4 intersects L at (0,p) and (5,t) What is the greatest possible value of slope L?
• Sep 17th 2008, 02:34 PM
ticbol
Quote:

Originally Posted by fabxx
Heyy, i need you guys' help on this too :(

xy coordinate plane graph x=y^2-4 intersects L at (0,p) and (5,t) What is the greatest possible value of slope L?

The x = y^2 -4 is a horizontal parabola that opens to the right. Its vertex is at (-4,0).

The line L intersects the parabola at (0,p) and (5,t).

Point (0,p) is (0,2) or (0,-2).
Point (5,t) is (5,3) or (5,-3).

There are only two possible L with positive slope.
The L with the greatest possible value of slope is the L that passes through (0,-2) and (5,3)
m = (-2 -3) / (0 -5) = 1

Check:
The slope of the L that passes through ((0,2) and (5,3) is
m = (2 -3) / (0 -5) = 1/5 --------less than the 1 of the L above.

The L that passes through (0,2) and (5,-3) has a negative value slope.