another integration help plz!

Question

anonymous · Answer

attachment

anonymous · Answer

97/36 not the right answer either :(

angela210793 · Answer

$$\int\limits_{-1}^{2}3t^3-t^2dx=3t^4/4-t^3/3$$

anonymous · Answer

yay right so far!

anonymous · Answer

where did i go wrong... lol

angela210793 · Answer

f(2)=3*2^4/4-2^3/3=12-8/3=36-8)/3=28/3
f(-1)=3/4+1/3=(9+4)/12=13/12

integral tht ur looking is 28/3-13/12=33/4
Yaaaaaay found it :):)

anonymous · Answer

so we dont have to multiply by 1/(b-a)?

angela210793 · Answer

why should u?
whn u have defined integrals all u have to do is replace the values and subtract wht u got from the highest one wht u got from the lowest value

anonymous · Answer

i found this example in my calc book the said: Find the average value of f(x)=3x^2-2x on the interval [1,4]

anonymous · Answer

when they explain it.. they multiplied the end answer by (1/3)

angela210793 · Answer

idk

anonymous · Answer

you do angela. he's finding the average mean... let me find the equation....

i think it's

$$1/b-a \int\limits_{a}^{b}f(x) dx$$

anonymous · Answer

if it just asked for say the area of the sum... then you wouldn' have to multiply it by

angela210793 · Answer

oh.....i was so on solving the integral tht i forgot wht the q was :$:$

anonymous · Answer

its cool... thanks guys

anonymous · Answer

haha it's ok. No one ever does those anymore. Hence why i had to look it up hahah

anonymous · Answer

did you get the answer?

anonymous · Answer

yep 11/4

anonymous · Answer

yeah i was going to say your work looks perfect