System of Linear Equations

sunnygirl37

New member
Joined
Sep 13, 2009
Messages
13
This one is:

Write a system of two linear equations with a solution of (-3,2) so that one line has a slope of 5 and the other line has a slope of -1/2.

This is what I did with the slope of 5.

y-y1=m(x-x1)

y-2=5(x+3)

y-2=5x+15
+2 +2
y=5x+17

This is what I've done with the slope of -1/2 (not sure if I did this one right or not)

y-y1=m(x-x1)

y-2=-1/2(x+3)

y-2=-1/2x-3/2
+2 +2
y=-1/2x-7/2

Here are my possible solutions:
A) y=5x and y=-1/2x
B) y=5x-17 and y=1/2x-1/2
C) y=5x-3 and y=-1/2x+2
D) y=5x+17 and y=-1/2x+1/2
E) None of these

I selected E because even though the first equation works in the first part of answer D, the second equation does not. I'm not sure if I did the second equation right.
 
sunnygirl37 said:
This one is:

Write a system of two linear equations with a solution of (-3,2) so that one line has a slope of 5 and the other line has a slope of -1/2.

This is what I did with the slope of 5.

y-y1=m(x-x1)

y-2=5(x+3)

y-2=5x+15
+2 +2
y=5x+17

This is what I've done with the slope of -1/2 (not sure if I did this one right or not)

y-y1=m(x-x1)

y-2=-1/2(x+3)

y-2=-1/2x-3/2
+2 +2
Check your arithmetic....(-3/2) + 2 is NOT -7/2
y=-1/2x-7/2

Here are my possible solutions:
A) y=5x and y=-1/2x
B) y=5x-17 and y=1/2x-1/2
C) y=5x-3 and y=-1/2x+2
D) y=5x+17 and y=-1/2x+1/2
E) None of these

I selected E because even though the first equation works in the first part of answer D, the second equation does not. I'm not sure if I did the second equation right.
 
Thanks for pointing that out!! That helps...I think the answer is C

y-2=-1/2x-3/2
+2 +2
y=-1/2x+1/2
 
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