Mathematics

Mathematics

Problem

Let g(x)=∫2xf(t) dtg(x)=\int_{2}^{x} f(t)\,dt, where ff is continuous on an open interval (a,b)(a,b). Which of the following conditions on ff is sufficient to conclude that gg is decreasing on (a,b)(a,b)? a) f(x)>0f(x)>0 for every xx in (a,b)(a,b) b) f(x)≤0f(x)\le 0 for every xx in (a,b)(a,b) c) f(x)<0f(x)<0 for every xx in (a,b)(a,b) d) f(x)<0f(x)<0 for at least one xx in (a,b)(a,b)

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