Math

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How do you solve this by linear combinations?

4x+3y=-8
3x-3y=15

  • Math -

    L1 : 4x+3y=-8
    L2 : 3x-3y=15

    Do L1+L2--> 7x=7 so x=1
    in L1 4*(1)+3y=-8
    3y=-12
    y=-4

    the couple of solution is(1,-4)

  • Math -

    How did you get x=1? by pugging it in with the 8 right?

  • Math -

    No. Add equation 1 (what mk-tintin labels L1) to equation 2, (L2) to obtain
    7x +0y = -8+15
    7x=7
    x=1

  • Math -

    doing L1+L2-->4x+3x+3y-3y=-8+15
    --->7x=7
    x=1
    do u understand?

  • Math -

    Oh i was looking at it all wrong alright i understand it a bit better now, doh was plugging in the wrong numbers haha. Sorry.

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