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    A question im trying to answer requires me to show that f(x)=0 has a root near to x=5 given that f(x)= x^3 - 5x^2 + 2.

    Ofcourse, the first step would be to sketch the graph but how would you do this ( without finding the roots of f(x)=0 anyway)?
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    (Original post by sonic23)
    A question im trying to answer requires me to show that f(x)=0 has a root near to x=5 given that f(x)= x^3 - 5x^2 + 2.

    Ofcourse, the first step would be to sketch the graph but how would you do this ( without finding the roots of f(x)=0 anyway)?
    You don't need to sketch it.

    Find f(4) and f(5).

    Look for a sign change.

    As f(x) is continuous, it must cross the x axis as it changes from negative to positive.
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    Thanks that makes more sense
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    (Original post by sonic23)
    Thanks that makes more sense
    Good.
 
 
 
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