<p>Pg.794 no.12</p>
<p>I kind of get it from reading the CB explaination but would like someone else's explaination so it is more clear. </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>(A) 3/4
(B) 3/2
(C) 9/4
(D) 3
(E) 9
**</p>
<p>Thanks for any help.</p>
<p>If y is directly proportional to x^2, then y = kx^2. k is a constant.</p>
<p>First, we need to find out what k is, and we do that by plugging in the values.</p>
<p>1/8 = k(1/2)^2
1/8 = k(1/4)
k = 1/2</p>
<p>Now since we know what k is, we can find out what x is when y = 9/2.</p>
<p>9/2 = kx^2
9/2 = 1/2(x^2)
9 = x^2
x = 3</p>