Solve the System of Equations: 3x - y = -10 and 9x - 3y = -15

Solve the following system of equations:

{3xy=109x3y=15 \begin{cases} 3x-y=-10 \\ 9x-3y=-15 \end{cases}

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Step-by-step video solution

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00:00 Solve
00:04 Let's multiply one of the equations by 3, so we can subtract between them
00:22 Now let's subtract between the equations
00:37 Let's group like terms
00:46 We got an illogical expression, therefore there is no solution
00:52 And this is the solution to the question

Step-by-step written solution

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1

Understand the problem

Solve the following system of equations:

{3xy=109x3y=15 \begin{cases} 3x-y=-10 \\ 9x-3y=-15 \end{cases}

2

Step-by-step solution

To solve this problem, let's apply the elimination method:

  • Step 1: Write down the given equations: 3xy=103x - y = -10 and 9x3y=159x - 3y = -15.
  • Step 2: Observe that the second equation is 3 times the first equation. Multiply the first equation by 3 for alignment: 3(3xy)=3(10)3(3x - y) = 3(-10) becomes 9x3y=309x - 3y = -30.
  • Step 3: Compare the two resulting equations: 9x3y=309x - 3y = -30 and 9x3y=159x - 3y = -15.
  • Step 4: Notice these equations suggest a contradiction as the left-hand side is the same (9x3y9x - 3y), but the right-hand sides are different (30-30 vs. 15-15).

As the comparison shows a contradiction, these lines are parallel and do not intersect.
Therefore, the system of equations has no solution.

3

Final Answer

There is no solution.

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\( \begin{cases} x+y=8 \\ x-y=6 \end{cases} \)

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