Pre-SAT Math HELP

<p>Unlike most of the CC community, my weakest section happens to be math, wherein I received only a 590 on the January test. I really hope to bring this up at least to a 650 on tomorrow's May test, so i'm sitting here working on practice problems in the blue book. </p>

<p>In this thread i'll be posting math questions I don't understand throughout the day...some of them are insanely simple, but I simply don't know how to do them. The bulk of questions i'm going to ask are algebra and functions, seeing as how I never really got a base knowledge of that in high school om n account of super slack teachers. </p>

<p>Thanks everyone for your help. Good luck to all taking tomorrow's test!</p>

<p>(from 2nd ed. SAT Official)</p>

<p>Prac. test 1, Sec. 3, Q. 14</p>

<p>If (2x-5)(2x+5) = 5, what is the value of 4x^2</p>

<p>A. -30
B -20
C. 10
D. 20
E. 30</p>

<p>I tried using formula a^2 - b^2 = (a + b)(a - b), but it wasn't really effective at all...I just began getting into complex polynomials</p>

<p>If (2x-5)(2x+5) = 5, what is the value of 4x^2</p>

<p>A. -30
B -20
C. 10
D. 20
E. 30</p>

<p>(2x-5)(2x+5) = 5</p>

<p>Multiply it out using FOIL <a href=“http://www.freemathhelp.com/using-foil.html[/url]”>http://www.freemathhelp.com/using-foil.html&lt;/a&gt;&lt;/p&gt;

<p>4x^2 + 10x - 10x - 25 = 5</p>

<p>Now simplify the terms, 10x cancels out
4x^2 - 25 = 5
4x^2 = 30</p>

<p>E</p>