Quick math question.

Test Preparation SAT Preparation
1

<p>If x and y are integers and xy + x^2 is odd, which of the following statements must be true?</p>

<p>I. x is odd
II. y is odd
III. x+y is odd</p>

<p>A - I only
B - III only
C - I and II
D - I and III
E - II and III</p>

<p>The answer is D (1 and 3) why? This is from the Jan 2008 SAT</p>

2

<p>That factors into x(x+y). If a product is odd, every single factor must be odd. Thus, x and x+y are odd. Moreover, this implies that y is even.</p>

3

<p>ahh thanks =)</p>