If a and b are constants, what is one solution of the equation (x + a)(x - b) = 0?
(1) a = 4
(2) b = 3
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if a & B are consteants MGMAT
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rommysingh
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Uva@90
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IS OA E ?rommysingh wrote:If a and b are constants, what is one solution of the equation (x + a)(x - b) = 0?
(1) a = 4
(2) b = 3
Pls post OA
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Uva
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Brent@GMATPrepNow
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Target question: What is one solution of the equation (x + a)(x - b) = 0rommysingh wrote:If a and b are constants, what is one solution of the equation (x + a)(x - b) = 0?
(1) a = 4
(2) b = 3
Statement 1: a = 4
This means the equation is (x + 4)(x - b) = 0
So, x = -4, is one possible solution to the equation.
Since we can answer the target question with certainty, statement 1 is SUFFICIENT
Statement 2: The b = 3
This means the equation is (x + a)(x - 3) = 0
So, x = 3, is one possible solution to the equation.
Since we can answer the target question with certainty, statement 2 is SUFFICIENT
Answer = D
Aside: I don't think I've seen an official GMAT question ask for ONE solution to a quadratic equation. Typically, we're either asked for the value of a variable or asked some yes/no question about the value of the variable (e.g., "Is x > 3?). What's the source?
Cheers,
Brent
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Max@Math Revolution
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If a and b are constants, what is one solution of the equation (x + a)(x - b) = 0?
(1) a = 4
(2) b = 3
==> In the original condition, x=-a, and thus we have 2 variables -a,b, meaning we need 2 equations to match the number of variables. Since we have 1 each for both (1), (2) the answer is likely C. Using both (1) & (2) together, x=-4,3 is our solution yet it is not unique, and thus NOT sufficient. Therefore the best answer is E
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If a and b are constants, what is one solution of the equation (x + a)(x - b) = 0?
(1) a = 4
(2) b = 3
==> In the original condition, x=-a, and thus we have 2 variables -a,b, meaning we need 2 equations to match the number of variables. Since we have 1 each for both (1), (2) the answer is likely C. Using both (1) & (2) together, x=-4,3 is our solution yet it is not unique, and thus NOT sufficient. Therefore the best answer is E
If you know our own innovative logics to find the answer, you don't need to actually solve the problem.
www.mathrevolution.com
l The one-and-only World's First Variable Approach for DS and IVY Approach for PS that allow anyone to easily solve GMAT math questions.
l The easy-to-use solutions. Math skills are totally irrelevant. Forget conventional ways of solving math questions.
l The most effective time management for GMAT math to date allowing you to solve 37 questions with 10 minutes to spare
l Hitting a score of 45 is very easy and points and 49-51 is also doable.
l Unlimited Access to over 120 free video lessons at https://www.mathrevolution.com/gmat/lesson
l Our advertising video at https://www.youtube.com/watch?v=R_Fki3_2vO8
