NOTE: I added some brackets in statement 1 to show the intent of the question.

kassim wrote:If y is positive, is y^x > 1000?

(1) y^x = 3000 + y^(x-1)
(2) x > 1000

Target question: Is y^x > 1000?

Given: y is positive

Statement 1: y^x = 3000 + y^(x-1)
If y is positive (as given), then y raised to ANY power will be POSITIVE.
In other words, y^(x-1) is POSITIVE, which means 3000 + y^(x-1) MUST BE GREATER THAN 3000
This means y^x > 3000, which means y^x > 1000
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: x > 1000
There are several values of x and y that satisfy statement 2. Here are two:
Case a: x = 1001 and y = 1, in which case y^x = 1^1001 = 1, which is NOT greater than 1000
Case b: x = 1001 and y = 2, in which case y^x = 2^1001, and 2^1001 IS DEFINITELY greater than 1000
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer = A

Cheers,
Brent