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Jinglander
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We can use counter examples to see why we can't divide, subtract or multiply inequalities.Jinglander wrote:MGMAT says never do this. Can someone explain why
- We know that 2<13 and 8<14, but when we subtract we get: (8-2)<(14-13), which simplifies to be 6<1 (no good
- Similarly, we know that 3<10 and 15<20, but when we divide we get: (15/3)<(20/10), which simplifies to be 5<2 (no good)
- Finally, we know that -3<-2 and 0<1, but when we multiply we get: (-3 x 0)<(-2 x 1), which simplifies to be 0<-2 (no good)
We can use logic to see why adding is okay. We'll use money as an example.
If Rod has more money than Bart (R>B), and Tod has more money than Lisa (T>L), then we also know that the combined wealth of Rod and Tod (R+T) will be greater than the combined wealth of Bart and Lisa (B+L).
In other word, if R>B and T>L then (R+T)>(B+L)
