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Mathematics 14 Online
OpenStudy (anonymous):

Simplify the expression

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?

OpenStudy (anonymous):

like would it be 4 + 3i?

ganeshie8 (ganeshie8):

Yes !

ganeshie8 (ganeshie8):

wat about numerator ?

OpenStudy (anonymous):

-3?

ganeshie8 (ganeshie8):

\(\large \sqrt{-9} = ?\)

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

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 ?

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):

\(\huge \frac{3i}{4+3i}\) \(\huge \frac{3i}{4+3i} \times \frac{4-3i}{4-3i}\) \(\huge \frac{12i-9i^2}{(4+3i)(4-3i)}\) \(\huge \frac{12i-9(-1)}{4^2 - (3i)^2}\) \(\huge \frac{12i+9}{16 - 9(-1)}\) \(\huge \frac{12i+9}{25}\)

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):

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 ?

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?

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 ?

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

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?

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

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):

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.

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.

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.

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):

\(\huge 4~\sqrt{24} - 4~\sqrt{8} + \sqrt{98}\) \(\huge 4~\sqrt{4 \times 6} - 4~\sqrt{4 \times 2} + \sqrt{49\times 2}\) \(\huge 8~\sqrt{ 6} - 8~\sqrt{2} + 7\sqrt{ 2}\)

ganeshie8 (ganeshie8):

combine like terms and simplify

OpenStudy (anonymous):

okay!

OpenStudy (anonymous):

7 square root of 2?

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