SOLUTION: Solve the system of equations using the substitution method. If the answer is a unique solution, present it as an ordered pair: (x, y). If not, specify whether the answer is “no s

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Question 170571: Solve the system of equations using the substitution method.
If the answer is a unique solution, present it as an ordered pair: (x, y). If not, specify whether the answer is “no solution” or “infinitely many solutions.”
3x + y = 7
4x – y = 21
Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
---answersystem%28x=4%2Cy=-5%29
Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
+system%28+%0D%0A++++3%5Cx+%2B+1%5Cy+=+7%2C%0D%0A++++4%5Cx+%2B+-1%5Cy+=+21+%29%0D%0A++We'll use substitution. After moving 1*y to the right, we get:
3%2Ax+=+7+-+1%2Ay, or x+=+7%2F3+-+1%2Ay%2F3. Substitute that
into another equation:
4%2A%287%2F3+-+1%2Ay%2F3%29+%2B+-1%5Cy+=+21 and simplify: So, we know that y=-5. Since x+=+7%2F3+-+1%2Ay%2F3, x=4.

Answer: system%28+x=4%2C+y=-5+%29.