Mathematics
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OpenStudy (anonymous):
Simplify the expression
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OpenStudy (anonymous):
ganeshie8 (ganeshie8):
start by simplifying the denominator
ganeshie8 (ganeshie8):
and rewrite numerator in terms of \(\large i\)
OpenStudy (anonymous):
The third answer is the correct one.
OpenStudy (anonymous):
how do i simplify the denominator?
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OpenStudy (anonymous):
like would it be 4 + 3i?
ganeshie8 (ganeshie8):
Yes !
ganeshie8 (ganeshie8):
wat about numerator ?
OpenStudy (anonymous):
-3?
ganeshie8 (ganeshie8):
\(\large \sqrt{-9} = ?\)
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ganeshie8 (ganeshie8):
nope, use this :
\(\large \sqrt{-1} = i\)
OpenStudy (anonymous):
hmmmm so 3?
ganeshie8 (ganeshie8):
\(\large \sqrt{-9} = \sqrt{-1} \times \sqrt{9} = i \times 3 = 3i \)
ganeshie8 (ganeshie8):
So, the simplified(not so) expression is :
\(\huge \frac{3i}{4+3i}\)
ganeshie8 (ganeshie8):
Multiply top and bottom by the conjugate of denominator : 4 - 3i
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OpenStudy (anonymous):
but that's not one of my options. do i have to do more work?
ganeshie8 (ganeshie8):
hahah yes more work :)
OpenStudy (anonymous):
OHHHH I GET IT NOW
OpenStudy (anonymous):
THANK YOU SO MUCH
ganeshie8 (ganeshie8):
what did u get ?
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OpenStudy (anonymous):
12 + 9i/7?
OpenStudy (anonymous):
or is it 9 + 12i/25?
OpenStudy (anonymous):
It's 9 + 12i/25
OpenStudy (anonymous):
Oh okay thanks!
ganeshie8 (ganeshie8):
\(\huge \frac{3i}{4+3i}\)
\(\huge \frac{3i}{4+3i} \times \frac{4-3i}{4-3i}\)
\(\huge \frac{12i-9i^2}{(4+3i)(4-3i)}\)
\(\huge \frac{12i-9(-1)}{4^2 - (3i)^2}\)
\(\huge \frac{12i+9}{16 - 9(-1)}\)
\(\huge \frac{12i+9}{25}\)
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OpenStudy (anonymous):
thaaaankkkk youuu so much for all your help! You're wonderful!
ganeshie8 (ganeshie8):
np :) u wlc !!
OpenStudy (anonymous):
are you busy? could you help me with a few more or no?
ganeshie8 (ganeshie8):
sure :) shoot...
OpenStudy (anonymous):
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OpenStudy (anonymous):
one question at a time
OpenStudy (anonymous):
what?
ganeshie8 (ganeshie8):
\(\huge 4 ~\sqrt[4]{48}\)
ganeshie8 (ganeshie8):
prime factorize the inside 48 :
48 = 2 x 24
= 2 x 2 x 12
= 2 x 2 x 2 x 6
= 2 x 2 x 2 x 2 x 3
= 2^4 x 3
ganeshie8 (ganeshie8):
right ?
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OpenStudy (anonymous):
Yep, okay so what do i do next?
ganeshie8 (ganeshie8):
\(\huge 4 ~\sqrt[4]{48}\)
\(\huge 4 ~\sqrt[4]{2^4 \times 3}\)
ganeshie8 (ganeshie8):
when u pull out 2^4 out of radical, it becomes 2
ganeshie8 (ganeshie8):
\(\huge 4 ~\sqrt[4]{48}\)
\(\huge 4 ~\sqrt[4]{2^4 \times 3}\)
\(\huge 4\times 2~\sqrt[4]{3}\)
OpenStudy (anonymous):
so it's the first option?
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ganeshie8 (ganeshie8):
Correct !
OpenStudy (anonymous):
Thanks!
OpenStudy (anonymous):
OpenStudy (anonymous):
Can you help me with that one?
ganeshie8 (ganeshie8):
The graph is opening UP, eh ?
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ganeshie8 (ganeshie8):
so it will have a positive leading coefficient
ganeshie8 (ganeshie8):
having that information,
which two options u can strike off ?
OpenStudy (anonymous):
the first two
ganeshie8 (ganeshie8):
Yes !!
ganeshie8 (ganeshie8):
answer must be between last two options,
lets see
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ganeshie8 (ganeshie8):
u should know the vertex form of parabola :
\(\large y = a(x-h)^2 + k\)
ganeshie8 (ganeshie8):
where, \((h,k)\) is the vertex
OpenStudy (anonymous):
True
ganeshie8 (ganeshie8):
Look at the graph, and can u identify the vertex coordinates ?
OpenStudy (anonymous):
-2, 3?
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ganeshie8 (ganeshie8):
first comes the x coordinate...
OpenStudy (anonymous):
3, -2
ganeshie8 (ganeshie8):
so vertex = (3, -2)
okay ?
ganeshie8 (ganeshie8):
yes :)
OpenStudy (anonymous):
OHHH SO IT'S THE THIRD ONE
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OpenStudy (anonymous):
wooohoooo yayy
ganeshie8 (ganeshie8):
you got it !! good job :)
OpenStudy (anonymous):
thanks! okay i have another one
OpenStudy (anonymous):
Edgar started with 2 poems in his journal. Then he started writing 3 poems each day. Which of the following graphs represents Edgar's poem writing?
OpenStudy (anonymous):
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OpenStudy (anonymous):
ganeshie8 (ganeshie8):
start value = 2
that means, the line will cut the y axis at 2
ganeshie8 (ganeshie8):
^^from that info,
which two options we can strike off ?
OpenStudy (anonymous):
the last two?
ganeshie8 (ganeshie8):
Correct, last two options are cutting y axis at 3. so they're wrong.
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ganeshie8 (ganeshie8):
that leaves the correct answer to be between first two
ganeshie8 (ganeshie8):
how to figure out which one is right ?
OpenStudy (anonymous):
yeah i dont know.
ganeshie8 (ganeshie8):
use the remaining info in quesiton
ganeshie8 (ganeshie8):
Then he started writing 3 poems each day.
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OpenStudy (anonymous):
Ohh it's the second option.
ganeshie8 (ganeshie8):
that means,
as u each day, the graph rises UP by 3
OpenStudy (anonymous):
right?
ganeshie8 (ganeshie8):
Excellent !!
OpenStudy (anonymous):
thank you.
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OpenStudy (anonymous):
OpenStudy (anonymous):
I only have like one more then I'm done hahaha
ganeshie8 (ganeshie8):
first step : prime factorize the stuff inside radicals
OpenStudy (anonymous):
how?
ganeshie8 (ganeshie8):
\(\huge 4~\sqrt{24} - 4~\sqrt{8} + \sqrt{98}\)
\(\huge 4~\sqrt{4 \times 6} - 4~\sqrt{4 \times 2} + \sqrt{49\times 2}\)
\(\huge 8~\sqrt{ 6} - 8~\sqrt{2} + 7\sqrt{ 2}\)
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ganeshie8 (ganeshie8):
combine like terms and simplify
OpenStudy (anonymous):
okay!
OpenStudy (anonymous):
7 square root of 2?