Question

The length of a rectangle is 2 more than its width. If the area of the rectangle is 20m squared, what are the dimensions of the rectangle, to the nearest tenth of a metre?

Answer 1

L=2+W
A=LW
A=(2+W)W
20=2W+W^2
0=W^2+2W-20
use quadratic
fr
aw^2+bw+C=0
w=(-b+/-sqrt(b^2-4ac))/2a

a=1
b=2
c=-20

w=(-2+/-sqrt(2^2-4(1)(-20)))/2(1)
w=(-2+/-sqrt(4+80))/2
w=(-2+/-sqrt(84))/2
w=(-2+/-2sqrt(21))/2
w=1+/-sqrt(21)
aprox
w=-3.58 or 5.58
cannot have negative width
w=5.58
round
w=5.6
sub
l=2+w
l=2+5.6
l=7.6


legnth=7.6m
width=5.6m