SOLUTION: Solve each system of linear equations by either substitution or by adding equations. x + y = −5 3x − 4y = 6

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Question 1133558: Solve each system of linear equations by either substitution or by adding equations.

x + y = −5
3x − 4y = 6
Found 3 solutions by Alan3354, addingup, MathLover1:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Multiply the 1st equation by 4, then add.
========
Or, multiply the 1st equation by -3, then add.

Answer by addingup(3677) About Me  (Show Source):
You can put this solution on YOUR website!
x + y = −5, x = -5-y
3x − 4y = 6
substitution:
3(-5-y) -4y = 6
-15-3y-4y = 6
-7y = 21
y = -3
and x = -5-(-3) = -2
Check:
x + y = -5
-2 + -3 = -5 Correct
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addition:
x + y = −5 multiply all times -3 and add to the next equation
3x − 4y = 6
.
-3x +- 3y = 15
+
3x - 4y = 6
-----------------
0x - 7y = 21
y = -3 of course, same answer as you get by substitution. Solve for x and you'll find it comes out to -2.
.
Happy learning

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!
x+%2B+y+=+-5+.......eq.1
3x+-4y+=+6.......eq.2
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start with
x+%2B+y+=+-5+.......eq.1...solve fo x
x+=+-y-5+.....eq.1a..substitute in eq.2

3%28-y-5%29+-4y+=+6.......eq.2 ..solve fo y
-3y-15+-+4y+=+6
-7y-15++=+6
-6-15++=+7y
-21++=+7y
y=-21%2F7
y=-3

go back to eq.1a, substitute y
x+=+-%28-3%29-5+.....eq.1a
x+=+3-5+
x+=+-2+


+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+-x-5%2C+3x%2F4-6%2F4%29+