Calculus Test Prep - Answers + Explanations

[hodeez]

Hi guys, I have a calculus test tomorrow and it'll be great if I can receive some answers + explanations! my review sheet is attached. if this is breaking the rules I am sorry.

hope this actually helps some other people too

 

[hodeez]

for #1
i got 3x^2-sin(xy^2)*2xy [dy/dx]*y^2
whadaya thinks?

 

[hodeez]

for #2) its log(x)/log4 b)then graph it with my TI89 then find the deriv @ .4


at work right now so no calculator on me =)
btw: does the TI89 have a test function == like the ti86?

 

[hodeez]

#3) f'(x)=2+cosx so we have to prove f'(x) is constantly positive or negative.. but how would we approach that?

 

[NateTG]

Originally posted by hodeez
#3) f'(x)=2+cosx so we have to prove f'(x) is constantly positive or negative.. but how would we approach that?

What's the minimum of cos(x) (assuming x is real)

 

[hodeez]

Originally posted by NateTG
What's the minimum of cos(x) (assuming x is real)

sorry I am not quite following you. on the y-axis it is -1, and on the x it can be -infinite. please correct me if I am wrong

 

[NateTG]

So, if the minimum value of cos(x) is -1, what is the minimum value of 2+cos(x)?

 

[hodeez]

lol wow i feel so dumb

thanks onward to the next question after i finish some quick job for my boss.

 

[hodeez]

i got x-4=y^3+y
so turn my ti89 to parametric mode and y1 = t^3+t
y2= -1 right? (since its g(3) 3-4 = -1)
then i trace for a zero?

 

[hodeez]

just came back from my test and i got confused on a question... find the deriv of x+sin(xy) i got (-sec(x)-y)/x but the calc gave me 1

thanks to all the people that replied and (attempted to) help

 

[himanshu121]

d/dx{x+sin(xy)} = 1 +cos(xy)[xdy/dx+y]

 

[hodeez]

oh my goddd what did i do? i messed up.. oh wells
thanks himanshu121 for reminding me of my errror