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If the function f(x)=x^2-k x+5 is increa...

If the function `f(x)=x^2-k x+5` is increasing on `[2,\ 4]` , then (a) `k in (2,\ oo)` (b) `k in (-oo,\ 2)` (c) `k in (4,\ oo)` (d) `k in (-oo,\ 4)`

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`f(x)=x^{2}-k x+5`
` frac{d(f(x))}{d x}=2 x-k=f^{prime}(x) `
For increasing function `f^{prime}(x)>0`
` 2 x-k>0 `
` ...
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