Please Help Me Or I Will Die Watch

qwertyqwerty12
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#21
Report Thread starter 11 years ago
#21
ok x^-1 is in(x) but if it is x^-2 then what is it?? ok if there is like a 3 in front of the whole thing like in prt screen bottom one in second column last question.

also i still dont get definite integrals can someone work thro one as an example from my questions or their own example as long as its similiar enough for me to apply to other questions
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generalebriety
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#22
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#22
(Original post by qwertyqwerty12)
ok x^-1 is in(x) but if it is x^-2 then what is it?? ok if there is like a 3 in front of the whole thing like in prt screen bottom one in second column last question.

also i still dont get definite integrals can someone work thro one as an example from my questions or their own example as long as its similiar enough for me to apply to other questions
I did a definite integral for you somewhere back on the last page.

x^-2 integrates just like the rest: add one to the power, and divide by it. \int x^{-2} \text{ d} x = \dfrac{x^{-2+1}}{-2+1} = \dfrac{x^{-1}}{-1} = -x^{-1} .
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Rabite
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#23
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#23
Oh, how civil.
Well.
Whatever.
Minus signs are gay.


It's always a minus sign.
sniff

[edit] Least I'm stupid anyway lol! You actually have a reputation to uphold. :p:
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qwertyqwerty12
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#24
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#24
no ok maybe i dont know what one is lol. but i was on about the questions in prt screen 2, where there is the numbers 2 and 0 etc that you have to multiply to the question.

also when there is a 3 or a diff number at the start of the integration question like in prt screen 2 last question.

ok and exp is integrated how?
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generalebriety
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#25
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#25
(Original post by qwertyqwerty12)
no ok maybe i dont know what one is lol. but i was on about the questions in prt screen 2, where there is the numbers 2 and 0 etc that you have to multiply to the question.

also when there is a 3 or a diff number at the start of the integration question like in prt screen 2 last question.

ok and exp is integrated how?
Yes, I did do a definite integral for you on the last page. It was the first thing I did. Go find it.

\int \exp (ax) \text{ d} x = \frac{1}{a} \exp (ax).

Constants just multiply in and out of the integral sign as you'd expect. a\int \text{f}(x) \text{ d} x = \int a\text{f}(x) \text{ d} x. So 3\int x \text{ d} x = \int 3x \text{ d} x as an example.
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qwertyqwerty12
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#26
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#26
ok so 3x^-1 is basically x^-1 with a 3, if you know what i mean

could you go through one of the examples on prt screen 2, or something similar i dont get how to use the numbers that you multiply by to get answers?
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generalebriety
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#27
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#27
(Original post by generalebriety)
I shall do your second one for you, since I've touched on it above. Get it into the right form, as above:
\displaystyle \int_1^2 \dfrac{1}{2} \sqrt{x} \text{ d} x = \int_1^2 \tfrac{1}{2} x^{1/2} \text{ d} x
and then integrate:
\displaystyle \int_1^2 \tfrac{1}{2} x^{1/2} \text{ d} x = \left[ \dfrac{\tfrac{1}{2} x^{3/2}}{3/2} \right]_1^2
and then put the limits in:
\displaystyle \left[ \dfrac{\frac{1}{2} x^{3/2}}{3/2} \right]_1^2 = \left( \dfrac{\frac{1}{2} 2^{3/2}}{3/2} \right) - \left( \dfrac{\frac{1}{2} 1^{3/2}}{3/2} \right)
and work that number out, whatever it is.
I've already done you one! :p:

Just integrate the thing as normal. Then put x = (top limit) and x = (bottom limit) and subtract the two, as above.
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Rabite
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#28
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#28
i dont get how to use the numbers that you multiply by to get answers?
Not sure what you mean, but... as for those constants, just think about what they mean:
\int 3 x^{-1} dx = 3\int x^{-1} dx
That means it's just "Triple the result of integrating x^-1, whatever that may be". Just ignore the constant and multiply by it when you're done with the integration (same as in differentiation).
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qwertyqwerty12
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#29
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#29
ok seriously i really appreciate all the help so far although i need to do some more pestering lol. ok i am not confident with second order derivatives like i cna do derivatives to first order most of the time. i will do it on paint and put it on blog in a few minutes, so plz stay online lol
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qwertyqwerty12
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#30
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#30
ok www.wakasas.blogspot.com

i added teh differentiation stuff i am having difficulty with i know how to do first order but not second. would really appreciate the help

also please show me an example being worked out from the prt screen that has 4 questions, the 3rd one down. the 2nd integration prt screen, where there are the digits you need to multiply by, thanks for the help, pos rep coming your way
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generalebriety
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#31
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#31
Don't see any differentiation stuff...
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qwertyqwerty12
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#32
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#32
yea sorry i cnt get it to publish for some reason i think i type it out on this

x
____
x+2


x
___
x-1


in(2x)+in(3x)

in (3x+5)+2x+1

exp(x)+exp(2x)

x^5+ 4x^3+ 2x+1

10+y+p+yp
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qwertyqwerty12
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#33
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#33
also i cnt even start to work these two out

x^2+2x+4
_________
x+2


x^2-6x+9
_________
x-3
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generalebriety
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#34
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#34
Do you know the quotient rule?
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qwertyqwerty12
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#35
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#35
nah i dont, although i appreciate help with doing second order on the above post more lol. your a real help if you can manage it
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insparato
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#36
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#36
Quotient Rule.

\displaystyle y = \frac{f(x)}{g(x)}

\displaystyle \frac{dy}{dx} = \frac{g(x)f'(x)-f(x)g'(x)}{[g(x)]^2}

I suggest you go look up about the chain rule, product rule and quotient rule.
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SsEe
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#37
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#37
(Original post by qwertyqwerty12)
also i cnt even start to work these two out

x^2+2x+4
_________
x+2


x^2-6x+9
_________
x-3
Try factorising the numerator in the second.
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