Question 75316This question is from textbook Alegbra 2 An Incremental Development
: Please help to solve
x + 3y = 7
xy = 2
This question is from textbook Alegbra 2 An Incremental Development
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! Please help to solve
x + 3y = 7
xy = 2
:
Arrange the 1st equation to = x
x + 3y = 7
x = 7 - 3y
:
Substitute (7-3y) for x in the 2nd equation, xy = 2:
y(7-3y) = 2
:
7y - 3y^2 = 2
:
0 = 3y^2 - 7y + 2; a quadratic equation that factors to:
:
(3y - 1)(y - 2) = 0
:
3y = +1
y = +1/3
and
y = +2
:
Find x when y = 1/3:
x = 7 - 3y
x = 7 - 3(1/3)
x = 7 -1
x = 6
;
Find x when y = 2
x = 7 - 3(2)
x = 7 - 6
x = 1
:
:
Test both sets of solutions in xy = 2
x=6,y=(1/3): 6(1/3) = 2
and
x=1, y=2: 1(2) = 2 also
:
How about this? Did you follow this OK? Any questions?
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