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Find all solutions to the following system of equations -y²+6y+x-9=0 ; 6y=x+27.Illustrate with a graph.

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  • mauricioalessandrell


    Answer:

    The solution to the system is the pair (9, 6)

    Step-by-step explanation:

    Hi!

    First, let´s write the system of equations:

    -y² + 6y + x -9 = 0

    6y = x +27

    The solutions of the system are the pairs (x, y) that satisfy both equations.

    Let´s take the second equation and solve it for x:

    6y = x +27

    Subtract 27 from both sides of the equation

    6y - 27 = x

    Now, we can replace x in the first equation and solve it for y:

    -y² + 6y + x -9 = 0

    -y² + 6y + 6y - 27 -9 = 0

    -y² + 12y - 36 = 0

    Notice that -y² + 12y - 36 = -(y - 6)², then:

    -(y - 6)² = 0

    y - 6 = 0

    y = 6

    (alternatively you can solve the quadratic equation using the quadratic formula).

    Now let´s find the value of x:

    x = 6y -27

    x = 6·6 -27

    x = 9

    The solution to the system is the pair (9, 6)

    Please see the attached figure. The point where the curves intersect is the solution to the system.