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Solve using elimination method -7x+5y=-56;-21x-2y=-168

  • math - ,

    thsi is how i would do it

    lets say equation 1 will be -7x + 5y = -56

    and equation 2 is -21x - 2y = -168

    nothign can cancel out if you llok at the equation so what i would do is multiply equation 1 by a negative 3 that way the -7x becomes a positive 21x to cancel out(but you have to multpliy everything in the equation by -3 not just the -7x)

    so you will have;

    21x -15y = 168

    now add the two equation together

    (21x - 15y= 168) + (-21x - 2y=-168)

    notice the x and the total on the right side of equal sign cancels leaving you with :

    -17y=o y=0 since 0 dvide by anything is still zero now choose any of your original equation and plug in 0 for y and solve for x

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