SOLUTION: Solve by the elimination method 0.3x-0-2y=4 0.4x+0.5y=-29/19

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Question 214867: Solve by the elimination method
0.3x-0-2y=4
0.4x+0.5y=-29/19
Answer by drj(1380) About Me  (Show Source):
You can put this solution on YOUR website!
Solve by the elimination method
0.3x-0.2y=4 Equation A
0.4x+0.5y=-29/19 Equation B

Step 1. Let's get rid of the fraction in Equation A by multiplying by 10 to both sides of equation to get

10%2A%280.3x-0.2y%29=10%2A4

3x-2y=40 Equation A-1

Step 2. Let's get rid of the fraction in Equation B by multiplying by 190 to both sides of equation to get

190%280.4x%2B0.5y%29=-190%2A29%2F19

76x%2B95y=-290 Equation B-1

Step 3. Multiply Equation A-1 by -47.5

47.5%283x-2y%29=47.5%2A40

142.5x-95y=1900 Equation A-2

Step 4. Add Equation B-1 and Equation A-2 to eliminate y to get

218.5x=1610

x=7.368421

Substitute x into 3x-2y=40 will yield

3%2A7.368421-2y=40

22.105263-2y=40

2y=-17.894737

y=-8.9473685

Step 5. ANSWER is x=7.368421 and y=-8.9473685

As a check let's solve this using substituion.

Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
We'll use substitution. After moving -0.2*y to the right, we get:
0.3%2Ax+=+4+-+-0.2%2Ay, or x+=+4%2F0.3+-+-0.2%2Ay%2F0.3. Substitute that
into another equation:
0.4%2A%284%2F0.3+-+-0.2%2Ay%2F0.3%29+%2B+0.5%5Cy+=+-1.52631578947368 and simplify: So, we know that y=-8.94736842105263. Since x+=+4%2F0.3+-+-0.2%2Ay%2F0.3, x=7.36842105263158.

Answer: system%28+x=7.36842105263158%2C+y=-8.94736842105263+%29.



Same result as before.

I hope the above steps were helpful.

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Good luck in your studies!

Respectfully,
Dr J