If , then
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Thank for sharing!!!
thank you for sharing
taking my GMAT next month, this helps!
got this wrong on my practice
Thanks for sharingThank you for sharing!!thanks for sharing
I used the trick of splitting the fraction: (a+b)/ab = a/(ab) + b/(ab). That simplifies quickly. Anyone else do it that way?
Yes! That's the cleanest way. After splitting you get 1/b + 1/a = 2, then solve for b.
I did that but then got stuck. How do you isolate b after that?
Why is (A) the answer? I got (B) somehow. Can someone explain?
Check your algebra. Start by multiplying both sides by ab: a + b = 2ab. Then group b terms: b - 2ab = -a, so b(1 - 2a) = -a. Then divide: b = -a/(1-2a) = a/(2a-1). That's (A).
This one was pretty straightforward. Just multiply both sides by ab and solve for b. Took me like 30 seconds.
I tried plugging in a=1 and got b=1. Only (A) gives 1 when a=1. That's a quick way to check.
What it tests
Your ability to manipulate linear and quadratic expressions, substitute unknowns, and solve equations under time pressure.
Common trap
Losing a sign when moving terms across the equals sign, or dividing both sides by a variable that could equal zero.