Algebra

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1,Sovle using the substitution method. Show your work. If the system has no solution or an infinite number of solutions,state this.
-x - 3y = -20
5x + 3y =40

2 Sovle 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
and
-2x + 3y = -37.5
-4x + 0y = -24

  • Algebra -

    form the 2nd equation: 3y = 40-5x
    sub into the first:
    -x - (40-5x) = -20
    -x - 40 + 5x = -20
    4x = 20
    x = 5
    sub into 3y = 40-5x
    3y = 40-25
    3y =15y=5
    so x=5, y=5

    2nd problem:
    -3x + 4y = 1
    -6x + 6y = -3
    multiply the first by -2 to get
    6x - 8y = -2
    add the 2nd
    -6x + 6y = -3 to get
    -2y = -5
    y = 5/2
    sub into original first
    -3x + 4(5/2) = 1
    -3x = 1 - 10
    x = 3

    for the last did you notice if you divide the 2nd equation by -4 you get the value of x ?
    I will let you finish it.

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