<p>If x+1/x=2, what is the value of x^2+1/x^2?
the answer is 2, I put 4 because I thought you would square everything, but I guess not.</p>
<h1>6, p.374</h1>
<p>If the slope of the line that passes thorugh the points (a,0) and (1,-2) is 1/2, what is the value of a?</p>
<h1>7, p.374</h1>
<p>One adult anf 10 children are in an elevator. If the adults weight is 4x the average weight of the children, then the adults wieght is what fraction of the total weight of the 11 people in the elevator?</p>
<p>Help would be greatly appreciated. Also, does anyone know a great book that focuses directly on Math?</p>
<ol>
<li><p>uh, if you square x + 1/x, you get x^2 + 1/x^2 +2=4, so x^2 + 1/x^2 = 2</p></li>
<li><p>the slope of the line is 2/(a-1)=1/2. solving for a, we get a=5.</p></li>
<li><p>uhh… the average weight of the children can be written as s/10, where s is the sum of all the kids’ weights. so the adult’s weight, which is 4 times that, is 2s/5. so the adult’s weight over the total weight is</p></li>
</ol>
<p>Then plug it in the second expression, get the answer.</p>
<ol>
<li>Use the formula for the slope of a line.</li>
</ol>
<p>(y2 - y1)/(x2 - x1). Plug in y2, y1, x2 and x1, set it equal to a and then solve</p>
<p>(-2-0)/(1-a)=1/2
-4=1-a
a=5</p>
<ol>
<li>Take one child’s average weight to be x. The total childrens’ weight would become 10x. The adult’s weight as said by the question is 4 times the average weight of a child so that would be 4x. So</li>
</ol>
<p>total weight in the elevator = childrens’ weight + adult’s weight
= 10x + 4x
= 14x.</p>
<p>In order to find the fraction of the adult’s weight, simply do adult’s weight/total weight which is</p>
<p>= 4x/14x
= 2/7.</p>
<p>Oh and Urc, why take the average weight to be s/10 and not simply s or x? That would be an unnecessary complication.</p>
<p>I don’t get how you did 1. Really, I did it in the simplest way. No need to square the equations or anything. Just solve for x and plug it in the other expression.</p>