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Question
Let f(x) = x2 + x + 1 and g(x) = sin x. Show that fog ≠ gof.
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Solution
(fog) (x) = f (g (x)) = f(sin x) = sin2 x + sin x + 1
and (gof) (x) = g (f (x)) = g (x2+ x + 1) = sin ( x2+ x + 1)
So, fog ≠ gof.
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