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9 August, 08:33

Solve the simultaneous Equation using the two

methods

4m=n + 7

3m + 4n+9=0

+1
Answers (1)
  1. 9 August, 09:03
    0
    Elimination method:

    4m = n + 7

    3m + 4n + 9 = 0

    First, let's get the equations in the same form.

    4m - n - 7 = 0

    3m + 4n + 9 = 0

    Now let's make multiply the first equation by 4 so we can eliminate n.

    16m - 4n - 28 = 0

    +3m + 4n + 9 = 0

    Now we can add the equations.

    16m + 3m - 4n + 4n - 28 + 9 = 0

    19m + 0n - 19 = 0

    19m - 19 = 0

    19m = 19

    m = 1

    Now we put m back into one (or both) of the original equations.

    4 (1) = n + 7

    4 = n + 7

    n = - 3

    If you plug m into the other equation, you get the same result.

    Substitution method:

    4m = n + 7

    3m + 4n + 9 = 0

    With this method, we plug one of the equations into the other one. I'm going to use m in the second equation as a substitute for m in the second equation.

    3m + 4n + 9 = 0

    3m = - 4n - 9

    m = (-4/3) n - 3

    Now I can substitute the right side into the first equation like so:

    4[ (-4/3) n - 3] = n + 7

    (-16n) / 3 - 12 = n + 7

    (-16n) / 3 = n + 19

    -16n = 3 (n + 19)

    -16n = 3n + 57

    0 = 16n + 3n + 57

    0 = 19n + 57

    0 = 19n/19 + 57/19

    0 = n + 3

    -3 = n

    And then we put that back into one of the original equations.

    4m = n + 7

    4m = - 3 + 7

    4m = 4

    m = 1

    Hopefully you learned something from this.
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