Question

If x>7 then -x>-7 is ___________

(a) possible

(b) certainly false

(c) certainly true

(d) depend on x

I have been asked this question during an online interview.

My question is taken from Algebraic Solutions of Linear Inequalities in One Variable and their Graphical Representation in section Linear Inequalities of Mathematics – Class 11

Answer 1

Correct choice is (b) certainly false

To explain I would say: If we multiply by negative number on both sides of inequality then sign of inequality will change i.e. if x>7 then (-1) x < (-1)7 => -x<-7.