tirupatibalaji wrote:
Is a^2 + b^2 > c^2 ?
(1) a^3 + b^3 > c^3
(2) a + b > c
The best way to deal with this problem is to plug in numbers. Remember, for DS questions when plugging in numbers, your
goal is to prove that the statement is not sufficient. So you should try to get a YES answer with one chosen number(s) and a NO with another.
Is a^2 + b^2 > c^2 ?(1) a^3 + b^3 > c^3.
Both YES and NO answers are easy to get:
If a and b are any positive numbers (for example a = b = 1) and c is zero, then the answer will be YES: 1^3 + 1^3 > 0^3 and 1^2 + 1^2 > 0^2;
If a and b are some positive numbers (for example a = b = 1) and c is a sufficiently large negative number (for example c = -10), then the answer will be NO: 1^3 + 1^3 > (-10)^3 and 1^2 + 1^2 < (-10)^2.
Not sufficient.
(2) a + b > c.
The same set of numbers will work for this statement as well:
If a and b are any positive numbers (for example a = b = 1) and c is zero, then the answer will be YES: 1 + 1 > 0 and 1^2 + 1^2 > 0^2;
If a and b are some positive numbers (for example a = b = 1) and c is a sufficiently large negative number (for example c = -10), then the answer will be NO: 1 + 1 > -10 and 1^2 + 1^2 < (-10)^2.
Not sufficient.
(1)+(2) We have one set of numbers which gives the answer YES for both statements and another set of numbers which gives the answer NO for both statements. Not sufficient.
Answer: E.
Similar question to practice:
https://gmatclub.com/forum/gmat-prep-ex ... 01358.htmlHope it helps.
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