We publish practice problems on our social media pages. Here's where you can find the correct answers—and explanations.

THE CORRECT ANSWER IS C.

If | *x *| = | 2*x* – 1 |, either *x* = 2*x* – 1 or –*x* = 2*x – *1. The solutions to these equations are 1 and 1/3, respectively. The only thing you need to recognize, however, is that the equation has two different solutions. The correct answer is therefore C.

THE CORRECT ANSWER IS C.

The question states that the corn on the north edge is shorter than the corn on the south edge, which is 50 inches tall. You are asked to find the height of the corn on the north edge, so the correct answer must be less than 50. Eliminate (D), which is too high. Often, at least one of the bad answers on these questions is the result you would get if you applied the percentage to the wrong value. To find the right answer, take 30% of 50 by multiplying 0.3 by 50 to get 15, then subtract that from 50. The corn on the north edge is 35 inches tall, which is choice (C).

THE CORRECT ANSWER IS B.

To find the value of *f*(3) + *f*(5), find the values of *f*(3) and *f*(5) separately: *f*(3) = 2(3)^{2} + 4 = 22 and *f*(5) = 2(5)^{2} + 4 = 54. So *f*(3) + *f*(5) = 76. You can tell that *f*(4) will be between 22 and 54, so you can cross out (A). If you Ballpark (C) and (D), putting 10 or 15 in the function will give you a number bigger than 100, and you're looking for 76, so (C) and (D) are too big. That means the answer is (B) by POE (Process of Elimination).

This is a system-of-equations question in disguise. Here's how to crack it: First, locate a piece of information you can work with. "The sum of three numbers,

–1(

Now solve:

. 1.6

Simplify by dividing both sides by 1.6 to get

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