inequality

[nafiul9090]

if X^2<81 and Y^2<25, what is the largest prime number that can be equal to X-2Y?

A. 3
B. 7
C 11
D 13
E 17

please help

[aneesh.kg]

The question does not say that X and Y has to be positive, or integers.
Therefore,
-9 < X < 9, -5 < Y < 5

The options are arranged in an ascending order of prime numbers, so let's try them in the reverse order to find the largest prime number.

Is 17 possible?
17 is possible when X = 8.5 , Y = -4.25 (and many such values) because (8.5) - 2(-4.25).
So, (E) is the answer.

[bryan88]

-9<X<9
-5<Y<5

Check if 17 is possible
If
X=8
Y=-4.5

Hence E

[nafiul9090]

yes the answer is E

[Birottam Dutta]

You have to understand that the trick here is to notice that x and y need not be positive or integers and then proceed. The answer comes easily then!

[sam2304]

Good one, I missed the catch Its so simple and doesn't take much time solving the problem once you understand the catch.

[nafiul9090]

You have to understand that the trick here is to notice that x and y need not be positive or integers and then proceed. The answer comes easily then!

i missed that part while answering the question...