Raxit85
If x and y are positive integers such that x² + y³ is a prime number less than 18, what is the value of y?
(1) x² + y² is a prime number.
(2) x² – y² is a prime number.
Given: x and y are positive integers such that x² + y³ is a prime number less than 18 There aren't many pairs of values that satisfy the condition
x² + y³ is a prime number less than 18So it might be useful (and faster) to list all possible pairs of values:
case i: x = 1 and y = 1
case ii: x = 2 and y = 1
case iii: x = 3 and y = 2
case iv: x = 4 and y = 1 Target question: What is the value of y? Statement 1: x² + y² is a prime number All
4 cases satisfy Statement 1.
So, we can see that
EITHER y = 1 or y = 2Since we can’t answer the
target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: x² – y² is a prime numberCases ii and iii satisfy Statement 2, which means
EITHER y = 1 or y = 2Since we can’t answer the
target question with certainty, statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined Cases ii and iii satisfy BOTH statements, which means
EITHER y = 1 or y = 2Since we can’t answer the
target question with certainty, the combined statements are NOT SUFFICIENT
Answer: E
Cheers,
Brent