tmua.me papers

tmua.me Medium Set F Paper 2 · Q12

Paper 2Logic & proofFunctions & graphs

A function ff is defined for every real number. Consider the statement:

For every real number k>0k>0, there exist distinct real numbers xx and yy such that f(x)=f(y)=kf(x)=f(y)=k and x+y<0x+y<0.

Which of the following is the logical negation of this statement?

AFor every k>0k>0, every pair of distinct real numbers x,yx,y satisfying f(x)=f(y)=kf(x)=f(y)=k has x+y≥0x+y\geq0.
BThere exist k>0k>0 and distinct real numbers x,yx,y such that f(x)=f(y)=kf(x)=f(y)=k and x+y≥0x+y\geq0.
CThere exists k>0k>0 such that every pair of distinct real numbers x,yx,y satisfying f(x)=f(y)=kf(x)=f(y)=k has x+y>0x+y>0.
DThere exists k>0k>0 such that, for every pair of distinct real numbers x,yx,y, either f(x)≠kf(x)\ne k or f(y)≠kf(y)\ne k or x+y≥0x+y\geq0.
EThere exist distinct real numbers x,yx,y such that, for every k>0k>0, either f(x)≠kf(x)\ne k or f(y)≠kf(y)\ne k or x+y≥0x+y\geq0.

Read the questions freely. Sign in to check your answer, see the worked solution and save your progress.