algebra

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show how to solve these problems:
1. 6x - y = -4
2x + 2y = 15 answer:x = 1/2
y = 7

2. x +y = 1 x = -1/3
2x - y = -2 y = 4/3

3. x - y = 3 x = 5/2
6x + 4y = 13 y = - 1/2

I just need to know how to solve these problems. Please show me how it is done.

  • algebra -

    Do them all the same way: either by combining equations in a way that cancels out one unknown, or by substitution.

    Here is how problem #3 can be solved:
    Substitute y + 3 for x in the second equation,
    6(y+3)+ 4y = 13
    10y + 18 = 13
    10 y = -5
    y = -1/2
    x = y+3 = 5/2

    Now you try the others.

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