SOLUTION: Can someone pls show me how to solve this equation using the addition/elimination process? 1.8x-2y=0.9 0.04x+0.18y=0.15

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Question 227730: Can someone pls show me how to solve this equation using the addition/elimination process?
1.8x-2y=0.9
0.04x+0.18y=0.15
Answer by drj(1380) About Me  (Show Source):
You can put this solution on YOUR website!
Can someone pls show me how to solve this equation using the addition/elimination process?
1.8x-2y=0.9 Equation A
0.04x+0.18y=0.15 Equation B

Step 1. Multiply by 0.09 to Equation A to both sides of the equation

0.162x-0.18y=0.081 Equation A1
0.04x%2B0.18y=0.15 Equation B
Step 2. Add Equations A1 and B to eliminate the y terms.

0.162x%2B0.04x-0.18y%2B0.18y=0.081%2B0.15

0.202x=0.231

Step 3. Divide by 0.202 to both sides of the equation

0.202x%2F0.202=0.231%2F0.202

x=1.143

Step 4. Substitute x=1.143 into Equation A 1.8x-2y=0.9 to solve for y.

1.8%2A1.143-2y=0.9

2.0584-2y=0.9

Step 5. Add 2y-0.9 to both sides of the equation

2.0584-2y%2B2y-0.9=0.9%2B2y-0.9

1.1584=2y

Step 6. Divide by 2 to both sides of the equation

y=0.5792

Step 7. ANSWER: The solution is x=1.143 and y=0.5792

As a check, use the substitution shown below which have the same results.

Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
We'll use substitution. After moving -2*y to the right, we get:
1.8%2Ax+=+0.9+-+-2%2Ay, or x+=+0.9%2F1.8+-+-2%2Ay%2F1.8. Substitute that
into another equation:
0.04%2A%280.9%2F1.8+-+-2%2Ay%2F1.8%29+%2B+0.18%5Cy+=+0.15 and simplify: So, we know that y=0.579207920792079. Since x+=+0.9%2F1.8+-+-2%2Ay%2F1.8, x=1.14356435643564.

Answer: system%28+x=1.14356435643564%2C+y=0.579207920792079+%29.


I hope the above steps were helpful.

For FREE Step-By-Step videos in Introduction to Algebra, please visit http://www.FreedomUniversity.TV/courses/IntroAlgebra and for Trigonometry visit http://www.FreedomUniversity.TV/courses/Trigonometry.

And good luck in your studies!

Respectfully,
Dr J
http://www.FreedomUniversity.TV