perplexus.info :: Just Math : Function at least 2

Function at least 2 (Posted on 2021-10-15)

Let a,b be reals and f(x)=ax+b+9/x. Prove that there exists x₀∈[1,9], such that |f(x₀)|≥2.

No Solution Yet Submitted by Danish Ahmed Khan

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what am I missing?

| Comment 1 of 4

The problem seems so completely trivial that I must be misinterpreting it greatly.

When I say a=1, b=1, x0=3, f(x0) = |f(x0)| =7

|f(x₀)|≥2, x0∈[1,9]

where have I gone wrong?

Thanks

Posted by Steven Lord on 2021-10-16 00:28:51

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