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manamesasher

  • 3 years ago

Solve the following system of equations graphically, find the graph 2x -y = -1 x + y = -2

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  1. manamesasher
    • 3 years ago
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  2. manamesasher
    • 3 years ago
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  3. manamesasher
    • 3 years ago
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    2?

  4. Calcmathlete
    • 3 years ago
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    Easiest way to do this is to plug in the point of intersection and if both equations are true, then it's the correct answer. For instance, let's check 2. \[2x - y = -1\]\[2(1) - (-1) = -1\]\[2 + 1 = -1\]\[3 ≠ -1\]THerefore, it isn't 2.

  5. manamesasher
    • 3 years ago
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    i was talking about the graph...

  6. Calcmathlete
    • 3 years ago
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    Also, if the point of intersection is the same in two choices, then you have to make sure the lines make sense.

  7. Calcmathlete
    • 3 years ago
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    And yes, 2 is incorrect since the solution set is also the point of intersection when graphed...

  8. manamesasher
    • 3 years ago
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    how about 3?..

  9. Calcmathlete
    • 3 years ago
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    Are you just guessing at this point?

  10. manamesasher
    • 3 years ago
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    no i'm asking if you can help me solve it...

  11. Calcmathlete
    • 3 years ago
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    Alright. I explained the process above... Let's take a look at choice 3... 2x - y = -1 Plus in the point of intersection, (-1, 1) 2(-1) - (1) = -1 -2 - 1 = -1 -3 ≠ -1 Do you see how the final equations ends up false since -3 does NOT equal -1?

  12. manamesasher
    • 3 years ago
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    ok. and choice 1, (-1, -1) 2(-1)-(-1)=-1

  13. manamesasher
    • 3 years ago
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    -1+-1=2

  14. manamesasher
    • 3 years ago
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    so it is choice 1..

  15. manamesasher
    • 3 years ago
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    thank you...

  16. amistre64
    • 3 years ago
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    my idea would be to use a knowledge of the equations to match the graph in this manner x + y = -2 notice this is pretty easy to turn to y = mx+b format y = -x-2 we need to find an option that has a line going thru y=-2 and a downill slope of -1

  17. Calcmathlete
    • 3 years ago
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    Um... \[2(-1) - (-1) = -1\]\[-2 + 1 = -1\]\[-1 = -1\]You should always check both equations by the way for the future, but it is indeed choice 1 :)

  18. manamesasher
    • 3 years ago
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    oh, ok sorry.. thanks again...

  19. amistre64
    • 3 years ago
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    1 and 3 fit the thru -2 part; and 3 is too steep for comfort

  20. robtobey
    • 3 years ago
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    A plot is attached.

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