SOLUTION: Solve linear system -4x-3y=-27 -4x+4y=8

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Question 214684: Solve linear system
-4x-3y=-27
-4x+4y=8
Answer by drj(1380) About Me  (Show Source):
You can put this solution on YOUR website!
Solve linear system

-4x-3y=-27 Equation A
-4x%2B4y=8 Equation B

Step 1. Subtract Equation B from Equation A to get rid of x terms to get

-7y=-35

Step 2. Divide by -7 to both sides to get

-7y%2F7=-35%2F-7

y=5

Step 3. Substitute y=5 into one of the equation to get x

{{-4x-3(5)=-27}}}

-4x-15=-27

Step 4. Add 15 to both sides to get x-terms on the left side and numbers on the right side.

-4x-15%2B15=-27%2B15

-4x=-12

Step 5. Divide by -4 to both sides of equation to get x

-4x%2F-4=-12%2F-4

x=3

Step 6. ANSWER: Solution is x=3 and y=5

We can also solve the equation using SUBSTITUTION:

Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
+system%28+%0D%0A++++-4%5Cx+%2B+-3%5Cy+=+-27%2C%0D%0A++++-4%5Cx+%2B+4%5Cy+=+8+%29%0D%0A++We'll use substitution. After moving -3*y to the right, we get:
-4%2Ax+=+-27+-+-3%2Ay, or x+=+-27%2F-4+-+-3%2Ay%2F-4. Substitute that
into another equation:
-4%2A%28-27%2F-4+-+-3%2Ay%2F-4%29+%2B+4%5Cy+=+8 and simplify: So, we know that y=5. Since x+=+-27%2F-4+-+-3%2Ay%2F-4, x=3.

Answer: system%28+x=3%2C+y=5+%29.



Same result as before.

I hope the above steps were helpful.

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And good luck in your studies!

Respectfully,
Dr J