EIV 4th pg 189 Inequalities

[mrollins]

If x>y, x<6 and y>-3, what is the largest prime number that could be equal to x+y?

Answer says 11, after simplifying to -3 < y < x < 6

I understand the simplification, but how do you get x+y=11. 5.6 and 5.4?

I realize it doesnt restrict to integers but it seems like that is implied in many explanations.

As an aside is there an errata section on the site with known errors in the texts?

Thanks!

[Ben Ku]

I realize it doesnt restrict to integers but it seems like that is implied in many explanations.

You should never assume variables are integers unless it's explicitly stated. The only places where a variable could be an integer are if that variable is even, odd, prime, or divisible by another integer.

If x>y, x<6 and y>-3, what is the largest prime number that could be equal to x+y?
Answer says 11, after simplifying to -3 < y < x < 6
I understand the simplification, but how do you get x+y=11. 5.6 and 5.4?

If we want the LARGEST prime sum, let's first find the largest possible sum. In this case, suppose x and y are both 6. The largest possible sum is 12. So the largest prime sum less than 12 is 11. Is there a way to get 11? You suggested a great way: if y = 5.4 and x = 5.6.

When you have inequality questions, you should approach them by finding the extreme values and working from there.

As an aside is there an errata section on the site with known errors in the texts?

There is currently not an errata for the Strategy Guides. We are compiling errors and revisions all the time, so they will be corrected in a future printing. You can contact the mgmat office to confirm whether something is indeed printed incorrectly.