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Simultaneous Equations help please?

Solve this simultaneous equation.

y=x+2

y=3xsquared

Please help me and it would help alot if you showed your

working out too. I can't do it...

5 Answers

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  • Bieber
    Lv 6
    1 decade ago
    Favorite Answer

    y=x+2

    y=3x^2

    So all you have to do here, is substitue 3x^2 in to the first equation's 'y':

    3x^2=x+2

    3x^2-x-2=0

    3x^2-3x+2x-2=0

    3x(x-1)+2(x-1)=0

    (3x+2)(x-1)-0

    x=-2/3 or 1

    Now sub 1 in to the first equatoin for x:

    y=3

    So one solution could be: (1,3)

    Now let's sub -2/3 in to the first equation for x:

    y=-2/3+2

    y=4/3

    And another solution is:

    (-2/3, 4/3)

    Have a nice day :)

    Source(s): Grade 10 Math
  • 1 decade ago

    if y=x+2 and y=3x^2, that means that x+2=3x^2, move them all to one side and you get 3x^2-x-2=0.

    This factors to (3x+2)(x-1)=0. In order for that expression to equal zero, one of the two factors must equal zero. So set 3x+2=0 and you solve that x=-2/3 also set x-1=0 and you get x=1.

    So your answers are x=-2/3 and x=1

  • jim
    Lv 4
    1 decade ago

    substitute 3x^2 for y in eq # 1 to get 3x^2 = x + 2 so 3x^2 - x - 2 = 0

    using then quadratic formula x = (1 +/- sqrt(1 + 24)/6 = (1 +/- 5)/6 = 1, -2/3

  • 1 decade ago

    y=x+2

    y=3x^2

    => x+2 = 3x^2

    0 = 3x^2 - x - 2

    0 = (3x + 2)(x - 1)

    x = -2/3 and 1, => y = 4/3 and 3

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  • 1 decade ago

    myalgebra.com

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