Help with ACT/SAT practive question...If a < b and c < 0, which of the following are true?

I need help with this act practive question..





If a %26lt; b and c %26lt; 0, which of the following are true?





I. ac %26gt; bc


II.a + c %26lt; b+c


III.a - c %26gt; b-c





I only


II only


III only


I and II only





Thanks alotHelp with ACT/SAT practive question...If a %26lt; b and c %26lt; 0, which of the following are true?
Definitely I and II.Help with ACT/SAT practive question...If a %26lt; b and c %26lt; 0, which of the following are true?
First strategy, if you can't remember properties of inequalities, is to choose some numbers that satisfy the assumptions:


a = 1, b = 2, c = -1 works.





Now check each of the inequalities, replacing each of the constants with the numbers we chose:





I. 1*-1 %26gt; 2*-1


Is -1 %26gt; -2 ?


Yes, so leave this one alone. It may be true or it may be false - this strategy doesn't tell us which.





II. 1 + -1 %26lt; 2 + -1


Is 0 %26lt; 1 ?


Yes, so leave this one alone too.





III. 1 - -1 %26gt; 2 - -1


Is 2 %26gt; 3?


No, so cross this answer out - it can't be true.





--------





The correct answer is one of


I only


II only


I and II only





Now, to answer these, you have to remember the properties. It turns out that the answer is ';I and II only';.





If you can't remember properties of inequalities though, take a guess. Even in the SAT, where you are penalized for guessing, it is worth it to take a guess if you can remove even one answer from the list of possibilities.
II only cause if a is less than b than a times c must be les than b times c even if c is less than 0
I and II





But try it out with actual values.
I and II only
I and II only

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