SOLUTION: please help to solve
x + 3y = 7
xy = 2
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Question 67784This question is from textbook An incremental Development
: please help to solve
x + 3y = 7
xy = 2
This question is from textbook An incremental Development
Found 2 solutions by adamchapman, ankor@dixie-net.com:
Answer by adamchapman(301) (Show Source): You can put this solution on YOUR website!
Rearrange xy=2 to get y=2/x.
Now put that in the first equation:
x+(3x/2)=7
solve:
2.5x=7
x=7/2.5
x=8
so y=2/8=1/4
Just like that!
I hope this helps.
Best Regards,
Adam
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
please help to solve
x + 3y = 7
Solve for x:
x = (7 - 3y)
:
Substitute (7-3y) for x in:
xy = 2
:
(7-3y) * y = 2
:
7y - 3y^2 = 2
:
Arrange as a quadratic equation:
-3y^2 + 7y - 2 = 0
:
Easier to factor if the 3y^2 is positive, multiply equation by -1
3y^2 - 7y + 2 = 0
:
Factors to:
(3y-1)(y-2) = 0
:
Two solutions for y
3y = +1
y = (1/3)
and
y = +2
:
Find the value of x using y = (1/3):
x + 3y = 7
x + 3(1/3) = 7
x + 1 = 7 - 1
x = +6
:
Find the value of x using y = 2
x + 3y = 7
x + 3(2) = 7
x + 6 = 7
x = 7 - 6
x = +1
:
We have two solution coordinates. x = 6: y =(1/3) and x = 1, y = 2
:
Note that both will satisfy the xy = 2 equation
:
Graphing you can see this is true also:
:
you can see they intersect and 6,(1/3) and 1,2
:
Did this help you understand this stuff?
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