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I need help with question 99 on the official GMAT Edition 13- how do we get the two solutions for the second equation...i can get 3/2 but the -1/2???
Here's the question:
If x(2x + 1) = 0 and (x + 1/2)(2x - 3) = 0, then x =
A) -3
B) -1/2
C) 0
D) 1/2
E) 3/2
OA = B
First recognize that, if AB = 0, then A=0, B=0 or they both equal 0
So, if x(2x + 1) = 0, then it must be true that x = 0, or 2x+1 = 0
If 2x+1 = 0, then x= -1/2
So, from this first equation, we know that x = 0 or x = -1/2
Similarly, (x + 1/2)(2x - 3) = 0, then it must be true that x + 1/2 = 0, or 2x - 3 = 0
If x + 1/2 = 0, then x= -1/2
If 2x - 3 = 0, then x= 3/2
So, from this second equation, we know that x = -1/2 or x = 3/2
When we examine the results of the two given equations, we can see that they both share the solution x = -1/2
So, the correct answer is x = -1/2 = B
Cheers,
Brent
