Posted by tina on .
A rectangular skating rink measuring 30m by 20m is doubled in area by adding a strip at one end of the rink and a strip fo the same width along one side of the rink. Find the width of the strips if the enlarged rink is still rectangular.

math 
Henry,
A = (30 + X) (20 + X) = 2(30 * 20),
X^2 + 30X + 20X + 600 = 1200 m,
X^2 + 50X + 600 = 1200,
X^2 + 50X + 600  1200 = 0,
X^2 + 50X  600 = 0,
Factor the Eq:
(X  10) (X + 60) = 0,
X  10 = 0,
X = 10.
X + 60 = 0,
X = 60.
Use the positive value of x:
X = 10 m = width of strips added,