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    The function f(x)= x^2-25 has domain (-∞,∞)
    The function g(x)=2x-3 has domain (0,∞)

    What is the domain and range of fg?
    So I have the domain of fg which is (0,∞) but I don't get why on the markscheme the range is (-25,∞)

    Domian of f is (0,∞) and the range of g is (-3,∞) which means we have to put the range of g into the function of f to get the range as it's the smallest...
    but because it's a curve shaped graph, it's not (-16,∞) so I don't really know what to do.. Please help! Thanks.
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    (Original post by BubbleLover98)
    The function f(x)= x^2-25 has domain (-∞,∞)
    The function g(x)=2x-3 has domain (0,∞)

    What is the domain and range of fg?
    So I have the domain of fg which is (0,∞) but I don't get why on the markscheme the range is (-25,∞)

    Domian of f is (0,∞) and the range of g is (-3,∞) which means we have to put the range of g into the function of f to get the range as it's the smallest...
    but because it's a curve shaped graph, it's not (-16,∞) so I don't really know what to do.. Please help! Thanks.
    If you put in (-3, infinity) into f. Then what possible values can f output? Hint: sketch the graph, what is the minimum point? What values does f output if you feed in number between -3 and infinity?
 
 
 
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