<p>pg. 794 #12</p>
<p>If y is directly proportional to x^2 and y=1/8 when x=1/2, what is the positive value of x when y=9/2?</p>
<p>answer is 3, plz explain how
thnxs =]</p>
<p>(1/8) = (1/4)</p>
<h2>(9/2) = x^2</h2>
<p>x^2 = ((9/2)x(1/4))/(1/8)
x^2 = 9
x = 3</p>
<p>We are told that y is directly poroportional to x^2.</p>
<p>1/8 is direct to (1/2)^2
1/8 is direct to 1/4
Set up ratio.
1/8 / 1/4 = 4/8 </p>
<p>That ratio is the same as the ratio 9/2 / X^2</p>
<p>Cross multiply and you end up with 72/2 / 4
36/4 = x^2 = 9</p>
<p>Sq root of 9 = x = 3.</p>
<p>I got confused with your method.</p>
<p>A:B
C:X</p>
<p>direct: X= (BC)/A
since it is proportional to x^2, just sqrt after you finish.</p>
<p>clean and easy, no room for error.</p>
<p>You really are confused. My method is the same as your method, i just took extra steps to show "why" . Clean and easy, no room for confusion.</p>
<p>I know, your overuse of /'s confused me :3</p>