Suppose that
f(x) and g(x) are functions on [a,∞), and that
0≤f(x)≤g(x) for all x∈[a,∞). Then we say f is bounded between
0 and g. Observe the following, based on the
inequality above:
- If ∫∞ag(x)dx converges, then
∫∞af(x)dx must also converge.
- If ∫∞af(x)dx diverges, then
∫∞ag(x)dx must also diverge.
- If ∫∞af(x)dx converges, we know
nothing about ∫∞ag(x)dx - it might
converge or diverge.
- If ∫∞ag(x)dx diverges, we know
nothing about ∫∞af(x)dx - it might
converge or diverge.
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