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    I got the equation down to 3(x-1)(x-1) > 0, the answer in the back of the book is 'x e r =(with a line through it) 1. Does that just mean the answer is anything apart from 1?
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    (Original post by physicshelpme)
    I got the equation down to 3(x-1)(x-1) > 0, the answer in the back of the book is 'x e r =(with a line through it) 1. Does that just mean the answer is anything apart from 1?
    Yes, because

    f(x)=3(x-1)^2

    is positive everywhere apart from at the point where x=1 (it touches the x axis here, and is therefore 0).
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    Thought so, okay the next one has confused me as well.

    'Find the values of x for which f(x) is an increasing function, given that f(x) equals:

    5x^3 + 12x
    I differentiated to get 15x^2 + 12 > 0
    3(5x^2 + 4) > 0 and now I don't know what to do
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    have a think about what happens to x if it is squared...
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    (Original post by the bear)
    have a think about what happens to x if it is squared...
    yea it will always be a positive answer so any value of x will have a result > 0 but how would i write that down as an answer?
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    just say that " for all values of x the derivative is positive... f'(x)>= 12 "
 
 
 
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