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Math Help - linear functions and their inverse.

  1. #1
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    linear functions and their inverse.

    how do i solve this problem?

    Find the linear function f with x-intercept 6 and f -1 (-8) = -3.

    i don't know how to do this at all.
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  2. #2
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    Are you in a course where you are expected to be able to do that? If so, do you know what a "linear function" is? Do you know any formulas for linear functions?
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    y=mx+b?
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  4. #4
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    Quote Originally Posted by FinalFantasy9291 View Post
    y=mx+b?
    Now use the given information, "with x-intercept 6" to get an equation with m and b in it. Call this equation (1).

    Do you know anything about inverse functions? If so, then you should know that if (-8, -3) lies on the graph of y = f^{-1}(x), then (-3, -8) lies on the graph of y = f(x). Use this to get another equation with m and b in it. call this equation (2).

    Now solve equations (1) and (2) simultaneously for m and b.
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  5. #5
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    Quote Originally Posted by FinalFantasy9291 View Post
    y=mx+b?
    Great! Of course, to give a specific function, you need to know m and b- two values.

    Also, you know f(6)= 0 and that f(-3)= -8. (Do you see why?) Set x= 6, y= 0 and then x= -3, y= -8 into y= mx+ b to get two equations to solve for m and b.
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