A small company produces both bouquets and wreaths of dried flowers. The bouquets take 1 hour of labor to produce, and the wreaths take 2 hours. The labor available is limited to 80 hours per week, and the total production capacity is 60 items per week. Write a system of inequalities representing this situation, where x is the number of bouquets and y is the number of wreaths.
Systems of inequalities!! Help with words problem!!!?
(1) 1x + 2y = 80 The time
(2) x + y = 60 The number of items
Don't know how you're supposed to do this.
Elimination:
Subtract (2) from (1)
x - x + 2y - y = 80 - 60
x-x=0, 2y-y=y, and 80-60=20 so
(3) y = 20
At this point I'd just substitute from (3) back into 2 and get x=40. But we're doing the elimination trip...
So multiply both sides of (2) by 2 and you get
(4) 2x+2y=120
Now subtract (1) from (4) and you get
2x-x + 2y-2y = 120-80.
Since 2x-x = x, 2y-2y=0, and 120-80=40,
(5) x = 40.
Substitution:
Solve (2) for x.
x + y = 60
Add -y to both sides and you get
(6) x = 60-y
Now, substituting from (6) into (1) you get
x + 2y = 80
(60-y) + 2y = 80
Because of the associative property of addition (a+b)+c =a+(b+c), that becomes
60 + (-y + 2y)=80
Doing the arithmetic,
(7) y=20
Substituting from (7) back into (2)
x+y=60
x + 20 = 60
x = 60-20 = 40
I'm not going to take the time to demonstrate that you get the same answers from matrices.
Reply:See below. Artie is correct.
Reply:x + 2y =%26lt; 80
x+y =%26lt; 60
x=%26gt; 0
y=%26gt;0
Reply:x+2y%26lt;80
x+y=60, so:
y=60-x
x+2(60-x)%26lt;80
x+120-2x%26lt;80
40%26lt;x
x%26gt;40
so:
y%26gt;20
Friday, February 3, 2012
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