OG 12 As X increases from 165 to 166,which of the following must increase? i)2x-5 ii)1-1/x iii)1/(x^2-x) A) i only B)iii only C)i and ii d)i and iii e) ii and iii

since x is an integer and increases 2x-5 will increase 1/x will decrease and hence 1-1/x increase x(x-1) increase..hence 1/(x^2-x) decrease so ans C

1) 2x-5 as x increases from 2x will inc for the given condition and therefore the value for 2x-5 will also inc 2) for the given condition 1/x decreases wrt to increasing value of x and therefore the value for 1-1/x will also inc 3)1/x(x-1) x(x-1) increases and the corresponding value of the exp dec so only 1 and 2 are increasing C

Time 1:51 IMO C I think what is being test here is people might start with x=165 and 166 and all(trap) which will take lot of time... rather than that... if we do x=1...2...3 then it will be possible to solve it,with in 2 minutes....

Can we follow this method? Instead of solving with the numbers given in prob,can we plug in another nums(like here 1...2...3) and solve? Ur suggestions please...

@Selango, Yes, you can plug in positive integers greater than 1. Generally when a question asks you how certain numbers behave, you can plug in other numbers that have similar behaviors. Along the number line, numbers can be divided into the following groups: {-infinity to -1} {-1 to 0} {0 to 1} and {1 to +infinity} Instead of dealing with decimals between 165 and 166, you could deal with 2 or 3. PS. The technique above wouldn't apply if the question is about even/odd of course, since that property divides numbers into different groupings. This is OG12 # 176. A couple of ways to solve are attached. -Patrick