<p>aps never give u extra information .if u dont use something they
say in the problem then u messed up somewhere</p>
<p>so heres my answer to
6b. f(-4)=2pi-3
f(4)=8-15e^(-4/3)</p>
<p>Darn, I ran out of time on the last part of 3. I had time to go back after the non-calc part and figured out that x=400, but I couldn’t calculate the total profit cause I didn’t have my calculator any more. Oh well, that should only be -1.</p>
<p>Ih8calc, </p>
<p>Did my last post make sense to you. That’s why you must use f(0) = 5 as part of your solution…</p>
<p>yea i guess… i kinda saw it as just doing the area of the graph w/o all that integral stuff. Y cant i just take the area of the semicircle and subtract that from a 2x4 rectangle. That is also considered area under the curve?</p>
<p>ih8calc, thats what I did, and I beleive points would be awarded, why wouldnt they be… its math, many paths often lead to a singular answer</p>
<p>Yes. But that represents the net change of the function f(x) from -4 to zero. We have to account for the point on f(x) that is given. The area you are finding tells us that f(x) increased its position (8-2pi) from -4 to zero and finished at a position of f(0) = 5. If we increased (8-2pi) and finished at 5 then we must have begun at f(-4) = 5 - (8-2pi) = -3 + 2pi. I would imagine that you will earn points for calculating the area under the curve.</p>
<p>did anyone figure how to do 4b? i was kind of stump by this question. I put in 2/pi or 4/pi (I don’t remember) as my answer in an attempt to receive points.</p>
<p>Here were my answers:</p>
<ol>
<li>
a) -.1 miles/min^2
b) represents the total distance traveled by Caren, in miles, from 0 to 12 minutes. Value = 1.8 miles
c) at t = 2 b/c v(t) changes sign from pos. to neg.
d) Caren lives 1.4 miles. Found by integrating v(t) from 0 to 12. Larry lives 1.6 miles. Found by integrating w(t) from 0 to 12. Therefore, Caren lives closer to school</li>
</ol>
<p>2.
a) 980 ppl
b) at t = 1.3629 b/c r ’ (t) changes sign from pos. to neg.
c) 387.5 hours
d) 1/980 * (760) = .7755 hrs/person</p>
<p>3.
a) Profit = 3000 - 500 = 2500
b) represents the cost, in dollars, of producing the last five meters of a 30 meter cable.
c) P(k) = 120K - int(6radx, x, 0, k)
d) Max of 16,000 dollars occurs at a cable of 400 meters in length</p>
<p>4.
a) 4/3
b) 4/pi
c) int ([rad(y) - .5y]^2, y, 0,4)</p>
<ol>
<li>
a)-3
b)8
c)18
d) tan line –> y=3x - 17
sec line –> y = (5/3) x - (31/3)
use fact that f(x) is concave down (since f’'(x) <0)</li>
</ol>
<p>6.
a) x = -2 and x = 0 b/c f '(x) changes from inc to dec or vise versa.
b)f(-4) = -3 + 2pi and f(4) = 8 - 15e^(-4/3)
c)abs max at 3ln(5/3) because end pts are mins and f '(x) changes from pos to neg at x= 3ln(5/3)</p>
<p>ANybody get anything similar?</p>
<p>@calculus guy, same answers as me.</p>
<p>Most of my answers are similar to yours. On problem 1, I misread the y-axis, which probably make me lose a lot of points. 5d, I did mention concave down, but plug in the number. 6c, i forgot to mention from pos to neg, I think. I think that you have over 90% correct.</p>
<p>For 5c, did you add 5 to f(4)?</p>
<p>for 5d: I evaluated both of my lines at x = 7 and found the values that they were looking for (4 and 4/3). I then justifies the < or > by using the tan line (overestimate) and secant line (underestimate) for a function that is concave down. Hope that helps clarify…</p>
<p>I got root 3 over 2 for 4b. Can anyone explain how to do it. (I just plugged in the integral for x)</p>
<p>Please PM me with explanition if u know or u can post it. It just really confused me. Im so mad there was no revolution question. I actually know how to do washers i hate cross sections lol</p>
<p>Fof 5c: I used 1(1) + 2(4) + 3(-2) + 5(3) = 18.</p>
<p>Feel better now that other people have gotten a lot of my answers!</p>
<p>4b: To find the volume of any solid you need to integrate the area formula of a cross section of the solid. Because they supplied a(x) as the area function I just integrated a(x) over the interval 0 to 2.</p>
<p>The antiderivative of sin(pix/2) = -(2/pi)*cos(pix/2). I evaluated this at 2 and 0 and then subtracted my results.</p>
<p>Antideriv @ 2 = -(2/pi)<em>cos(pi(2)/2) = -(2/pi)</em>cos(pi) = -(2/pi)<em>-1 = 2/pi
Antideriv @ 0 = -(2/pi)</em>cos(pi(0)/2) = -(2/pi)<em>cos(0) = -(2/pi)</em>1 = -2/pi</p>
<p>Difference: (2/pi) - (-2/pi) = (4/pi).</p>
<p>****. i screwed this up big time. its my best subject too. Please tell me the curve is gonna be frickin generous. Would you guys say this year 70+ is def safe for a 5?</p>
<p>lol im an idiot i just plugged in 4/3 for x and got sin 2pi/3 so i put root3/2. thanks for explaining it. I definately got a 3 now. What do u guys think the curve will be.</p>
<p>I hope that the curve would be less than 70 or where most of us get 5’s.</p>
<p>I think i got in the 50’s do u think that will be a 4?</p>
<p>for 4b. the integral of A(x) from 0 to 2 is 2 and if you multiply it by the base it is 8/3</p>
<p>But i thought u just plugged the integral in for x. Like when the cross sections r squares thats all you do bc the area of a square is x^2 and to find the volume with square cross sections u do the integral (f(x)-g(x))^2 so thats why i just plugged in the integral for x. Im so confused. That was the dumbest question ever!</p>