Anonymous
Anonymous asked in Science & MathematicsMathematics · 1 decade ago

solve by substitution method?

4x+7=48

-4x+y=16

not sure how I am doing this. but the answer is wrong.

pleas help

2 Answers

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  • TomV
    Lv 7
    1 decade ago
    Favorite Answer

    Shouldn't that first equation be "4x+7y=48"?

    IF so, add the two equations to get:

    8y = 64

    from which y = 8

    substituted into the first equation gives

    4x + 56 = 48

    or

    x = -2

    ...

  • 1 decade ago

    You can work out what x = from the first equation

    4x + 7 = 48

    4x = 41

    x = 41/7

    Now it substitute it into the second one instead of x:

    -4x + y = 16

    y - 4(41/7) = 16

    y = 16 + 4(41/7)

    y = 39.43 (4sf)

    Hmm yeah I think tom may be right that you meant 4x + 7y = 48....fml

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