Math

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Use the functions f(x)=x+4 and g(x)=2x-5 to find the specified functions.

(g x f)^-1

  • Math -

    Please state in words your notation

    (g x f)^-1 I assume you do not mean the reciprocal of g times f.

  • Math -

    let y = g x f
    = (x+4)(2x-5)

    y = 2x^2 + 3x - 20

    so the inverse of that is
    x = 2y^2 + 3y - 20
    2y^2 + 3y - 20 - x = 0

    which by the way is not a function

    to solve for y you will have to use the quadratic formula and

    y = (-3 ± √(9-8(-20-x))/4
    etc.

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