On referring to your explanation for problem in the link attached below.
https://www.beatthegmat.com/a-data-from- ... tml#359007
Is A positive?
1. x^2 - 2*x + A is positive for all x
2. A*x^2 + 1 is positive for all x
For the above problem. On referring to your explanation as below::::
It's key to understand exactly what a statement is telling you.
(1) x^2 - 2*x + A is positive for all x
To satisfy this statement, we have to have an A that makes the expression positive for EVERY POSSIBLE value of x.
Well, if x=0, then the expression simply equals A. So, in order for the statement to be positive when x=0, A must be positive. Therefore, to guarantee that the expression is ALWAYS positive, regardless of the value of x, we have to have a positive A: sufficient, eliminate B, C and E.
My Doubt:
How come you arrived at A as answer by testing for x=0 alone.
for example take
x=2 , then statement 1(x^2 - 2*x + A is positive for all x
) gives 4-4+ A = A and since statement is +ve A must be positive (Good or x=0,2)
x=3 , then the statement 1 gives 9-6+A= 3+ A so, inorder for this (3+A) to be positive A can be -1 , -2 or any positive number?
In this case we cannot say A is +ve , then A is wrong answer ....Am i right????
Please correct me if iam wrong here.....
https://www.beatthegmat.com/a-data-from- ... tml#359007
Is A positive?
1. x^2 - 2*x + A is positive for all x
2. A*x^2 + 1 is positive for all x
For the above problem. On referring to your explanation as below::::
It's key to understand exactly what a statement is telling you.
(1) x^2 - 2*x + A is positive for all x
To satisfy this statement, we have to have an A that makes the expression positive for EVERY POSSIBLE value of x.
Well, if x=0, then the expression simply equals A. So, in order for the statement to be positive when x=0, A must be positive. Therefore, to guarantee that the expression is ALWAYS positive, regardless of the value of x, we have to have a positive A: sufficient, eliminate B, C and E.
My Doubt:
How come you arrived at A as answer by testing for x=0 alone.
for example take
x=2 , then statement 1(x^2 - 2*x + A is positive for all x
) gives 4-4+ A = A and since statement is +ve A must be positive (Good or x=0,2)
x=3 , then the statement 1 gives 9-6+A= 3+ A so, inorder for this (3+A) to be positive A can be -1 , -2 or any positive number?
In this case we cannot say A is +ve , then A is wrong answer ....Am i right????
Please correct me if iam wrong here.....
