How does the 1 come into the picture?

Test Preparation SAT Preparation
1

<p><a href="http://imgur.com/t1mWh.jpg%5B/url%5D"&gt;http://imgur.com/t1mWh.jpg&lt;/a&gt;&lt;/p>

2

<p>It’s because when you pull out an (xy)^y from that equation you’re pulling (xy)^y from -(xy)^y which leaves -1. Try multiplying the final answer out to see for yourself.</p>

3

<p>I don’t understand this at all, what math knowledge am I missing?</p>

4

<p>Factoring.</p>

5

<p>^
Distributive property</p>

6

<p>Some help:
x^2 + x
Factored: x ( x + 1 )</p>

<p>to a higher power:</p>

<p>x^3 + x
Factored: x ( x^2 + 1 )</p>

<p>The problem is the same thing as the last expression, but instead of x, it is (2x), and insated of just 3 and 1 as the exponents, it is 3y and y.</p>

7

<p>Alternative Method: - Plugging in numbers!</p>

<p>Let x = 3
Let y = 2</p>

<p>Original Equation:
(2x)^(3y) - (2x)^(y)
(6)^(6) - (6)^(2)
46656 - 36
46620</p>

<p>Answer choice C:
(2x)^(y)<a href=“6”>(2x)^(2y) - 1</a>^(2)[(6)^(4) - 1) <— from here this should become very familiar
36[1296 - 1]
36[1295]
46620</p>

<p>Obviously this method is the more taxing method. It will take probably 2-3 minutes even if you work efficiently. In addition there is a much bigger margin of error. However, you said, “I don’t understand this at all”, so this is a suitable alternative for now, but I highly suggest you learn the algebraic way.</p>

8

<p>AvidStudent, your alternative didn’t take long at all actually, just plug’em up in the calculator. Only thing is I need to recognize that I can do that. I’ll try to learn the algebra, but it’s difficult to find comprehensive resources to teach yourself.</p>

9

<p>Out of curiosity, what math class are you in this year? Factoring was covered quite extensively in my Algebra II class.</p>