Another SAT blue book math problem that was not in the consolodated list

Test Preparation SAT Preparation
1

<p>Hi,</p>

<p>pg 463 #17</p>

<p>Let the operation ↑ be defined by a ↑ b = (a+b) / (a-b) for all numbers a and b, where a is not equal to b.</p>

<p>If 1 ↑ 2 = 2 ↑ x, what is the value of X?</p>

<p>I tried to do it and got 1 but that is not the right answer (correct answer is 4)</p>

2

<p>1 arrow 2 = (1+2)/(1-2)= -3</p>

<p>(2+x)/(2-x) = -3
cross multiply
-6+3x= 2+ x
-8= -2x
x=4</p>

3

<p>Thanks, I got -3 but then put 3… which messed me up.</p>