Solve X and Y in System: 1/2x + 7/2y = 10, -3x + 7y = 12

Solve the above set of equations and choose the correct answer.

{12x+72y=103x+7y=12 \begin{cases} \frac{1}{2}x+\frac{7}{2}y=10 \\ -3x+7y=12 \end{cases}

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve the system of equations
00:03 Multiply by 2 to eliminate fractions
00:15 Now this is the system of equations
00:21 Subtract between the equations
00:29 Negative times negative always equals positive
00:32 Isolate X
00:40 This is the value of X, now substitute to find Y
00:49 Isolate Y
01:03 This is the value of Y
01:11 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the above set of equations and choose the correct answer.

{12x+72y=103x+7y=12 \begin{cases} \frac{1}{2}x+\frac{7}{2}y=10 \\ -3x+7y=12 \end{cases}

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Multiply the first equation to make the coefficients of yy equal to easily eliminate yy.
  • Step 2: Subtract one equation from the other to eliminate yy and solve for xx.
  • Step 3: Substitute the value of xx back into one of the original equations to solve for yy.

Now, let's work through each step:
Step 1: Multiply the first equation 12x+72y=10\frac{1}{2}x + \frac{7}{2}y = 10 by 2 to eliminate fractions:
x+7y=20 x + 7y = 20

Step 2: Use the second equation as is: 3x+7y=12-3x + 7y = 12. Subtract the equation x+7y=20x + 7y = 20 from 3x+7y=12-3x + 7y = 12 to eliminate yy:
(3x+7y)(x+7y)=1220 (-3x + 7y) - (x + 7y) = 12 - 20
4x=8 -4x = -8
Solve for xx:
x=2 x = 2

Step 3: Substitute x=2x = 2 back into the equation x+7y=20x + 7y = 20:
2+7y=20 2 + 7y = 20
Subtract 2 from both sides:
7y=18 7y = 18
Divide both sides by 7:
y=1872.57 y = \frac{18}{7} \approx 2.57

Therefore, the solution that satisfies both equations is (x,y)=(2,2.57)(x, y) = (2, 2.57).

The correct choice is x=2,y=2.57\boxed{x=2, y=2.57}.

3

Final Answer

x=2,y=2.57 x=2,y=2.57

Practice Quiz

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Solve the following equations:

\( \begin{cases} 2x+y=9 \\ x=5 \end{cases} \)

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