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cwrw238
I'm helping my nephew with a function question and i'm stuck on one part - I should know this really. f(x) = x^2 - 19, domain = (-INF, 0) g(x) = 1 -(1/2) x, domain = (6, INF). Find range of f and g which i found to be (-19, INF) and (-INF, -2). Find fg - which I got to be (1 - (1/2)x)^2 - 19. Write down the domain and range of fg. - i'm a bit confused about this part.
I've done this stuff before but cant remember this bit.
hi. i think i can help. consider the intersection of the two domains
what is the intersection of the two domains?
well they dont intersect - which makes me think that the domain is that of g (6, INF)
the domain is the null set. and thus, it has not range either
does that make sense to you?
hmm - not sure to be honest - i'm not saying you're wrong - but i'll have to go back to the books thanx for your comments
sure, the product, quotient and sums of two functions need to have intersecting domains
otherwise the function is not defined. I hope that helps. Take care.
I've checked this out - because the domain of 'inner' function is (6.infinity) the composite function must have same domain - they intersect at that range of values hers a rough (lol) drawing