I have tried everything I can think of, and it just won't work. I even managed to eliminate x, only to think myself in circles, and have my calculator decide it will no longer use fractions. I had to turn it into fractions, as my teacher will not take anything that isn't exact, and she basically doesn't allow the use of decimals in most cases, because she doesn't allow rounding in nearly any cases. I found some asinine fraction to be the answer for y, but I'm really not sure it was correct, since it was such an odd #.
1.5x + 0.7y = 0.5
2.2x - 0.6y = -7.4
hi!!!
It sounds a little odd that your teacher doesn't allow you to use much decimal numbers...... =(
Anyway..
Does it help to know x+y?
If yes, try this; multiply the first equation with 2 and then add two equations. It'll be sth like 0.8(x+y)=-6.4.
This tells you that one of the variables is a negative number. Try to find the value of x-y and you can solve it very quickly.
Well, you said you have a value for y, though it's strange try it with this equation and get a X value then put it into the first two equations and what happens.
good luck!
Change it into fractions first:
(3/2)x+(7/10)y=(1/2)
(11/5)x-(3/5)y=-(37/5)
And because the denominators are all the same, multiply through:
15x+7y=5
11x-3y=-37
And solving for "x" in each yields:
x=(5-7y)/15
x=(-37+3y)/11
And setting them equal to one another:
(5-7y)/15=(-37+3y)/11
Thus:
11(5-7y)=15(3y-37)
And solving for "y":
55-77y=45y-555
55=122y-555
610=122y
Thus:
y=5
And plugging this into the first equation:
15x+7y=5
Yields:
15x+7(5)=5
15x=-30
Thus:
x=-2
1.5x + 0.7y = 0.5
1.5x = 0.5 - 0.7y (you then divide both sides by 1.5)
x = (1/3) - (7/15)y
2.2x - 0.6y = -7.4
2.2 ((1/3) - (7/15)y) - 0.6y = -7.4
(22/30) - (154/150)y - (6/10)y = - (74/10)
(110/150) - (154/150)y - (90/150)y = - (1110/150) (you times both sides by 150)
- 154y - 90y = - 1110 - 110
- 244y = - 1220
y = 5
x = (1/3) - (7/15)y
x = (1/3) - (7/15)(5)
x = (1/3) - (7/3)
x = - (6/3)
x = - 2
x = -2, y = 5
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