WynWynn
Solve the system of equations by the addition method.
Choose one answer.
a. (-2, 1)
b. (-2, -1)
c. (2, 1)
d. (2, -1)
Delete
Share
This Question is Closed
WynWynn
Best Response
You've already chosen the best response.
2
gandalfwiz
Best Response
You've already chosen the best response.
1
THe addition method is adding one term to another to get a variable to cancel out.
gandalfwiz
Best Response
You've already chosen the best response.
1
You can multiply the equations by various numbers first to get the variables just right so they cancel
gandalfwiz
Best Response
You've already chosen the best response.
1
It doesn't matter what variable we choose to cancel out. Let's do x
WynWynn
Best Response
You've already chosen the best response.
2
ok!
gandalfwiz
Best Response
You've already chosen the best response.
1
We need the number in front of the first x to be the opposite of the second x, like 5, -5, or -3, 3, so they'll add to zero.
gandalfwiz
Best Response
You've already chosen the best response.
1
Lets multiply the first equation by 5 and the second one by -3 so we'll get a 15x and a -15x
gandalfwiz
Best Response
You've already chosen the best response.
1
5(-3x+7y=-1)
-15x+35y=-5
gandalfwiz
Best Response
You've already chosen the best response.
1
second equation: -3(-5x-4y=14)
15x+12y=-42
gandalfwiz
Best Response
You've already chosen the best response.
1
Do you see what I did there?
gandalfwiz
Best Response
You've already chosen the best response.
1
wynwyn? uthere?
WynWynn
Best Response
You've already chosen the best response.
2
Yes yes yes i see!!
gandalfwiz
Best Response
You've already chosen the best response.
1
kk... now u just add the equations together.
-15x+35y=-5
+
15x=12y=-42
gandalfwiz
Best Response
You've already chosen the best response.
1
(4 second equation: supposed to be 15x+12y=-42)
gandalfwiz
Best Response
You've already chosen the best response.
1
so. -15x+15x=0.
35y+12y=47y
-5+-42=-47
0+47y=-47
gandalfwiz
Best Response
You've already chosen the best response.
1
Now just solve for y.
47y=-47
y=-1
gandalfwiz
Best Response
You've already chosen the best response.
1
Now that u know what y is, plug it back into an equation (it doesn't matter which) and solve for x
gandalfwiz
Best Response
You've already chosen the best response.
1
-3x+7y=-1
-3x+7(-1)=-1
-3x-7=-1
-3x=6
x=-2
WynWynn
Best Response
You've already chosen the best response.
2
ok
gandalfwiz
Best Response
You've already chosen the best response.
1
It looks like you want your final answer to be an ordered pair, like a point on a graph. a point is always in the form (x,y), so your final answer is -2,-1
gandalfwiz
Best Response
You've already chosen the best response.
1
choice b
WynWynn
Best Response
You've already chosen the best response.
2
Thank you so much!!!
gandalfwiz
Best Response
You've already chosen the best response.
1
welcome! Medal?
gandalfwiz
Best Response
You've already chosen the best response.
1
tnx :)
WynWynn
Best Response
You've already chosen the best response.
2
no problem! =D