Expert: Richard J. Raridon - 5/9/2007

Question
1.) The length if a rectangle is 1 cm longer than its width.   If the diagonal of the rectangle is 4 cm, what are the dimensions(the length and width) of the rectangle?

2.) The equation h=16t^2 + 112t gives the height of an arrow, shot upward from the ground with an initial velocity of 112ft/s, where t is the time after the arrow leaves the ground.  Find the time it takes for the arrow to reach a height of 180ft.?

3.) A ball is thrown upward from the roof of a building 100m tall with an intial velocity of 20m/s.  When will the ball reach a height of 80m?

4.) The demand equation for a certain type of printeris given by
d= -200p + 35,000
the supply equation is predicted to be
s= -p^2+400p-20,000
find equilibium price?  

Answer
1) L = W+1 and  L^2 +W^2 = 4^2 so W = 2.284 and L = 3.284
2) the correct equation is h = 112t -16t^2
so you have 180 = 112t -16t^2 and solve for t, t = 2.5s
3) h = h0 +vt -(1/2)gt^2
80 = 100 +20t -4.9t^2 so t = 4.91s
4) First of all, don't use commas in equations.         d=s so you have p^2 -600p +55000 = 0 and = 113 or 487