Official papers

Official 2020 Paper 2 · Q12

Paper 2Logic & proofCalculus

Which one of A–F correctly completes the following statement?

Given that a<ba<b, and f(x)>0f(x)>0 for all xx with a<x<ba<x<b, the trapezium rule produces an overestimate for ∫abf(x) dx\displaystyle\int_a^b f(x)\,\dd x …

A… if f′(x)>0f'(x)>0 and f′′(x)<0f''(x)<0 for all xx with a<x<ba<x<b
B… only if f′(x)>0f'(x)>0 and f′′(x)<0f''(x)<0 for all xx with a<x<ba<x<b
C… if and only if f′(x)>0f'(x)>0 and f′′(x)<0f''(x)<0 for all xx with a<x<ba<x<b
D… if f′(x)<0f'(x)<0 and f′′(x)>0f''(x)>0 for all xx with a<x<ba<x<b
E… only if f′(x)<0f'(x)<0 and f′′(x)>0f''(x)>0 for all xx with a<x<ba<x<b
F… if and only if f′(x)<0f'(x)<0 and f′′(x)>0f''(x)>0 for all xx with a<x<ba<x<b

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