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simultaneous equation with x squared?

y = 1 - 2x

y = x^2 -3x-5

please , just first step

5 Answers

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  • ?
    Lv 7
    8 years ago
    Favorite Answer

    1-2x=x^2-3x-5

    x^2-x-6=0

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

    x=3 or x=-2

    apply this to the 1st equation

    when x=3 y=1-2(3)=-5

    when x=-2 y=1-2(-2)=5

    answer x=3,y=-5 or x=-2,y=5

  • 8 years ago

    You have to substitute the linear equation into the quadratic.

    Since y is common to both equations, you can write this:

    1-2x=x^2-3x-5

    and from this:

    x^2-x-6=0

    Then solve this as you would any other quadratic.

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

    Then:

    x-3=0

    x=3

    and x+2=0

    x=-2

    Substitute these values into the linear equation:

    y=1-2x

    y=1-2(3)

    y=-5

    and y=1-2(-2)

    y=5

    so you get the two solutions, which should be written as pairs:

    x=3 and x=-2

    y=-5 y=5

    Source(s): AS level maths and further maths student
  • 8 years ago

    from the given 2 equations we have

    x^2 -3x-5=1 - 2x

    =>x^2-x-6=0

    =>x^2-3x+2x-6=0

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

    therefore either x=2 or x=3

    when x= - 2 then from first equation we have y=1 - 2*(-2)= 5

    and when x=3 then from first equation we have y=1 - 2*3= - 5

  • Yash
    Lv 4
    8 years ago

    y = 1 - 2x --------1)

    y = x^2 - 3x - 5 ----------2)

    Substitute eqn 1) in eqn 2)

    1 - 2x = x^2 - 3x - 5

    x^2 - 3x + 2x - 5 - 1 = 0

    x^2 - x - 6 = 0

    x^2 - 3x + 2x - 6 = 0

    x(x - 3)+2(x - 6) = 0

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

    x = 3 or x = -2

    Substitute these two values in eqn 1)

    When x = 3

    y = 1 - 2x = 1 - 2(3) = 1 - 6 = -5

    When x = -2

    y = 1 - 2x = 1 - 2(-2) = 1 + 4 = 5

    (x,y) = (3,-5) or (x,y) = (-2,5) -----------Answer

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  • 8 years ago

    as requested, first step only !

    y = y which is -

    x^2 - 3x - 5 = 1 - 2x

    then combine like terms and solve or factor the quadratic

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