<p>Pg. 425 #8</p>
<p>if x^2 + y^2 = 73 and xy = 24, what is the value of (x + y)^2</p>
<p>hint: (X+y)^2 = x^2 + y^2 + 2xy</p>
<p>So how do you know that's true? What rule is that? I got the answer after your hint, but I don't understand how (X+y)^2 is equal to x^2 + y^2 + 2xy. Thanks btw.</p>
<p>(x+y)^2 is FOIL</p>
<p>(x+y)(x+y) = x^2 + 2xy + y^2</p>
<p>Ah! Thank you so much that aspect was really troubling me!</p>
<p>Got another for you guys :)</p>
<p>Pg. 425 #10</p>
<p>If 30 percent of 40 percent of a positive number is equal to 20 percent of w percent of the same number, what is the value of w?</p>
<p>A) 80
B) 60
C) 50
D) 15
E) 10</p>
<p>I set up the problem as follows: (0.3)(0.4k) = (0.2)(wk), where k is the positive number. I got 6 though which isnt an answer....</p>
<p>I think the problem is the concept of percent.</p>
<p>We can solve it the way you set it up:
(.3)(.4)(k)= (.2)(w)(k)</p>
<p>Canceling out k from both sides, then simplifying, we get:
0.12=.2w</p>
<p>Solving for w, we get w=.6, which is 60%, or choice B.</p>