Solve using the elimination method. Show your work. If the system has no solution or an infinite number of sol?

Solve using the elimination method. Show your work. If the system has no solution or an infinite number of solutions, state this.

-3x+4y=1, -6x+6y=-3

THIS IS WHAT I GOT

multiply yh first equation -3x+4y=1 by 2------- -6x+8y=1

then add 2nd equation -6x+6y=-3..... 12y=-2

y=-6

then -3x+4(-6)=1....-3x+-24=1

x=25...... am i right (25,-6) please help

6 Answers

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  • 9 years ago
    Favorite Answer

    Rewriting the equations:

    -3x+4y=1

    -6x+6y=-3

    Multiply (-3x+4y=1) by 2 to get: -6x+8y=2

    Once again rewriting:

    -6x+8y=2

    -6x+6y=-3

    Subtract the second equation from the first equation to eliminate x:

    -6x+8y=2

    -(-6x+6y=-3) (Here, distribute.)

    2y=5, y=2.5

    Plugging y in to equation 1 and rearranging:

    -3x+4*2.5=1

    -3x+10=1

    -3x=-9

    x=3

    So, x=3 and y=2.5.

    Your solution is (3,2.5)

  • Anonymous
    9 years ago

    Remember what you do to one side of the equation, you have do it on OTHER side also.

    Your approach is right but you need to fix one thing. Look at your first step and there is the problem in your evaluation.

    Second problem that I see is that you are adding -6 and -6, which doesn't cancel out but adds up to -12. Fix it by either multiplying your first equation by -2 or if you multiply by 2 then SUBTRACT instead of adding the equations.

    Hope these guidelines help, I would give away the answer, but I think this would be more helpful.

  • Anonymous
    9 years ago

    You have at least one error. Correctly:

    -6x+8y =2 (not 1)

    -6x+6y = 3

    2y= -1

    y= -1/2

    Substituting, -3x - 2 = 1

    solving, x= -1

  • 9 years ago

    Your mistake was adding -6x to -6x which would be -12x

    multiply the first equation by -2 and try again

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  • Como
    Lv 7
    9 years ago

    6x - 8y = - 2

    -6x + 6y = - 3_____ADD

    -2y = - 5

    y = 5/2

    6x = - 2 + 20

    6x = 18

    x = 3

    x = 3 , y = 5/2

  • 9 years ago

    divide second equation by -2 to get

    3x-3y=3/2

    then add it to first one

    (-3x+4y) + (3x-3y)=(1)+(3/2)

    y=5/2

    etc.

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