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tina d
tina d asked in Science & MathematicsMathematics · 1 decade ago

Solve the system by addition 2x – 9y = 4 x – 2y = –3?

3 Answers

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  • Anonymous
    1 decade ago
    Favorite Answer

    2x - 9y = 4

    -2x + 4y = 6

    -5y = 10

    y = -2

    x = -7

  • ?
    Lv 7
    1 decade ago

    2x-9y=4

    x-2y=-3

    Multiply the second equation by -2

    2x-9y=4

    -2x+4y=6

    -------------Add

    -5y=10

    y=-2

    Substitute -2 for y back into either original

    equation. I'll use the first.

    2x-9(-2)=4

    2x+18=4

    2x=4-18

    2x=-14

    x= -7

    Check:

    2x-9y=4

    2(-7)-9(-2)=4

    -14+18=4

    4=4

    x-2y=-3

    -7-2(-2)=-3

    -7+4=-3

    -3=-3

    We're done. the answers are correct

  • Anonymous
    1 decade ago

    2x - 9y = 4

    x - 2y = - 3 (multiply this line by -2)

    -2x + 4y = 6

    Solve by addition...

    9y - (+4y) = 4 + 6

    therefore -5y = 10 or y = -2

    by substitution... if y = - 2 then x = -7

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