Mathematics
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OpenStudy (anonymous):
Least upper bound , Greatest lower bound
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OpenStudy (anonymous):
@ganeshie8
ganeshie8 (ganeshie8):
watch this quick,
we can do an example after that :)
OpenStudy (anonymous):
I watched it >.<
OpenStudy (anonymous):
The same on u sent last night?
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ganeshie8 (ganeshie8):
no, this is different and much better and short
ganeshie8 (ganeshie8):
7 minutes.... watch it :)
OpenStudy (anonymous):
Okay, So i have a feeling that -1 will be one of the answers because that is one of the factors that did not have remainder 0
OpenStudy (anonymous):
\[x^4+10x^3+33x^2+38x+8\]
ganeshie8 (ganeshie8):
yes, we have found roots for this already right ?
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OpenStudy (anonymous):
Yes but we did not find bounds
OpenStudy (anonymous):
atleast i dont think we did
ganeshie8 (ganeshie8):
once we have roots, finding bounds is piece of cake
OpenStudy (anonymous):
Well lets bake a cake then! lol
ganeshie8 (ganeshie8):
lol, below are ur roots :
\(\large -4, ~-2, ~-2-\sqrt{3}, -2 + \sqrt{3}\)
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ganeshie8 (ganeshie8):
whats the lowest value ?
whats the greatest value ?
ganeshie8 (ganeshie8):
the lowest value of roots is \(-4\),
so the "greatest lower bound" is \(-4\)
ganeshie8 (ganeshie8):
the highest value of roots is \(-2 + \sqrt{3}\)
so the "least upper bound" is \(-2 + \sqrt{3}\)
ganeshie8 (ganeshie8):
we're done.
ganeshie8 (ganeshie8):
let me knw if smthng doesnt make sense..
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OpenStudy (anonymous):
Do you want ice cream with your cake?
OpenStudy (anonymous):
Because im going to reward myself for understand what you just said muhaha
OpenStudy (anonymous):
Shall we do another?
OpenStudy (anonymous):
Oh, you left ( ._.)
ganeshie8 (ganeshie8):
awww both are irresitables xD
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ganeshie8 (ganeshie8):
sorry somebody knocked the door... had to attend to that lol
ganeshie8 (ganeshie8):
lets do the next q :)
OpenStudy (anonymous):
"Attend to that " sounds like you murdered them haha
ganeshie8 (ganeshie8):
lol hahah wish i could >.<
ganeshie8 (ganeshie8):
wats the next q ha ?
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OpenStudy (anonymous):
Lol nice way to change the subject ;)
OpenStudy (anonymous):
sec itll take a second to type
ganeshie8 (ganeshie8):
:) take ur time
OpenStudy (anonymous):
\[p(x)=x^5+3x^4-9x^3-3x^2-52x-60\]
we need to find :
p
q
p/q
# of positive roots
# of negative rootss
least upper bound
greateest lower bound
roots
ganeshie8 (ganeshie8):
evil professor :/
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OpenStudy (anonymous):
seriously though. that 60 is about to make me cry
ganeshie8 (ganeshie8):
start by counting sign changes in p(x) and p(-x)
OpenStudy (anonymous):
1?
ganeshie8 (ganeshie8):
\(p(x)=x^5+3x^4-9x^3-3x^2-52x-60\)
yes, sign changes in p(x) = 1
so there will be EXACTLY 1 positive real root for p(x)
ganeshie8 (ganeshie8):
next, find f(-x), and count the sign changes
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OpenStudy (anonymous):
its either 2 or 6
OpenStudy (anonymous):
Is that not right?
ganeshie8 (ganeshie8):
\(p(x)=x^5+3x^4-9x^3-3x^2-52x-60 \)
\(p(-x)=-x^5+3x^4+9x^3-3x^2+52x-60 \)
ganeshie8 (ganeshie8):
sign changes in p(-x) is 4
so there can be 4 or 2 or 0 negative real roots
OpenStudy (anonymous):
Yeah i knew that, I was just testing you
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ganeshie8 (ganeshie8):
P = 60
Q = 1
P/Q = \(\pm 1, \pm 2, \pm 3, \pm 4, \pm 5, ......\)
OpenStudy (anonymous):
>.>
ganeshie8 (ganeshie8):
pick ur fav number
+1 or -1 ?
OpenStudy (anonymous):
-1
ganeshie8 (ganeshie8):
\(
\begin{array}{}
-1|&1&3&-9&-3&-52&-60\\
&&&&\\
\hline
&&&&\\
&1&&&
\end{array}
\)
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OpenStudy (anonymous):
ill do it !
OpenStudy (anonymous):
|dw:1396543448725:dw|