SAT Prep

Answer to Math #3

Answer: D
Difficulty: Hard

This is a perfect problem to use the Plugging In Numbers (PIN) strategy.  To use this strategy, simply choose a number (not usually 0 or 1) to plug in for x.  Plug the number into the given expression and then plug it into each of the answer choices to see which one (or ones) match.  A word of caution with this method: Always make sure to check EVERY answer choice.  Sometimes, more than one will work and you will need to try a different number in order to determine which answer choice is correct.

Ex. Choose x = 2

\frac{6(2)-5}{2+2} = \frac{12-5}{4} = \frac{7}{4}

A)  \frac{6-5}{2}=\frac{1}{2}\neq \frac{7}{4}

B)  6-\frac{5}{2} = 6(\frac{2}{2})-\frac{5}{2} = \frac{12}{2}-\frac{5}{2} = \frac{7}{2}\neq \frac{7}{4}

C)  6-\frac{5}{2+2} = 6-\frac{5}{4} = 6(\frac{4}{4})-\frac{5}{4} = \frac{24}{4}-\frac{5}{4} = \frac{19}{4} \neq \frac{7}{4}

D) 6-\frac{17}{2+2} = 6-\frac{17}{4} = 6(\frac{4}{4})-\frac{17}{4} = \frac{24}{4}-\frac{17}{4} = \frac{7}{4} . Yay!!