MathRevolution wrote:

Is (r²)x>0?

1) r⁵ = 1

2) x > 0

*An answer will be posted in 2 days.

Target question: Is (r²)(x) > 0? Statement 1: r⁵ = 1 This tells us that r = 1, however we don't know the value of x.

Let's TEST some values.

Case a: r = 1 and x = 1, in which case (r²)(x) = (1²)(1) = 1. Here,

(r²)(x) is GREATER than 0Case b: r = 1 and x = -1, in which case (r²)(x) = (1²)(-1) = -1. Here,

(r²)(x) is NOT GREATER than 0Since we cannot answer the

target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: x > 0 Okay, x is POSITIVE, however we don't know the value of r.

Let's TEST some values.

Case a: r = 1 and x = 1, in which case (r²)(x) = (1²)(1) = 1. Here,

(r²)(x) is GREATER than 0Case b: r = 0 and x = 1, in which case (0²)(x) = (0²)(1) = 0. Here,

(r²)(x) is NOT GREATER than 0Since we cannot answer the

target question with certainty, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined Statement 1 tells us that r = 1, which means

r² = 1Statement 2 tells us that x is POSITIVE

This means that (r²)(x) = (

1³)(POSITIVE) = SOME POSITVE #. In other words,

(r²)(x) is GREATER than 0Since we can answer the

target question with certainty, the combined statements are SUFFICIENT

Answer =

Cheers,

Brent

_________________

Brent Hanneson – Founder of gmatprepnow.com