<p>BB page 657 number 18.</p>
<p>There are threads that contain through explanations of this question, but i still have one more question left.</p>
<p>Take a look at this equation
106 = (6+d^2) - (d-10)^2</p>
<p>Now, we want to expand the (d-10)^2 right? so i did and i got D^2+20D+100
However, somebody posted it as D^2+20D-100. He appears to be correct, but i do not see why. Does the - sign in front of (d-10)^2 have anything to do with it?What am i missing? help.</p>
<p>Its D^2 -20D + 100</p>
<p>Both of you are wrong.</p>
<p>^beat me to it :D</p>
<p>All you have to do is to set up three equations and solve for d and c. Then plug and chug.</p>
<p>How did you figure that out? Amazing.
btw kho thats what i got and it wouldn’t work unless its -100.</p>
<p>A minus sign before a parenthesis kind of reverses the signs of the parts inside the parenthesis, just so you know…
So without the parenthesis it would be
106 = 6 +d^2 - d^2 + 20d - 100
Therefore d = 10.</p>
<p>C would equal 106 and the height would be 70 feet at t = 1.</p>
<p>(d-10)(d-10)</p>
<p>(d^2 -20d + 100)</p>
<p>HOWEVER, since there is a - in front of the thing -(d^2-20d+100)</p>
<p>it would turn into</p>
<p>-d^2+20d-100</p>