 # Bluebook Math Questions

<p>Something weird happened. This is not the first post, this is actually an answer to the second post.</p>

<h1>17.</h1>

<p>There are 9 equal intervals, therefore, each interval is equal to 1/9th. The marked interval is 6/9th. The square root of x is equal to 2/3. This means that REGULAR x is equal to (2/3)^2. Regular x is equal to 4/9. This question got me once before . . .</p>

<h1>13</h1>

<p>x + y is even
(x + y)^2 + x + z is odd.</p>

<p>(A) x is odd
(B) x is even
(C) If z is even, then x is odd
(D) If z is even, then xy is even
(E) xy is even</p>

<p>Test them. </p>

<p>A- If x is odd, y must be odd, because x + y is even. That would mean that this even number squared would have an odd number added to it. However, (A) does not specify if z is odd or even, so it can't work. With z not specified, x can be even or odd.</p>

<p>B- if x is even, y must also be even because x + y is even. This even number, when squared, is also even. Add an even number (x), and it is even. However, (B) does not specify if z is even or odd, therefore x can be even or odd. You can easily get this by using the principle from A. B is wrong.</p>

<p>C- C is different. If x is odd, then y must also be odd. These two, when squared, will become even. We add x, and it becomes odd again because x is odd in this. Now, remember that your final result must be odd. For an odd number to remain odd, you must add an even number, therefore, z must be even. C specifies this condition as well, and is for that reason the correct answer.</p>

<p>Once you have A, you can eliminate B and testing C gives you the right answer.</p>

<p>I am a longitme reader of this board but this is my first post.
I need help on number 17 on page 535 and number 13 on page 550 in the blue book.
Thanks</p>

<p>How did you reply to this post before I posted??? It says my post is at 11:10 and yours is at 11:09?</p>

<p>Excuse my error, this is a common mistake </p>

<p>The square root of x is equal to 2/3. This means that REGULAR x is equal to (2/3)^2. Regular x is equal to 4/9. This question got me once before . . .</p>

<p>Thanks alot for the help.</p>

<p>No prob. (10 char)</p>

<p>[ul]550 / 13 /[/ul]</p>

<p>For the sake of simplicity let's substitute "n=0" for "n is even", since zero is an even number.</p>

<p>(x+y) is even =>
(x+y) = 0 =>
(x+y)^2 = 0</p>

<p>(x+y)^2 + (x+z) is odd =>
0 + (x+z) is odd => (x+z) is odd.</p>

<p>(x+z) is odd and z is even =>
(x+z) is odd and z=0 => x must be odd.</p>