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
A. 3
B. 7
C 11
D 13
E 17
please help
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.
Its so simple and doesn't take much time solving the problem once you understand the catch.
