anonymous
  • anonymous
okay help with this problem and then one more and I wont need anymore help tonight. (2-3i(3-i)-(4-i)(4+i)
Algebra
  • Stacey Warren - Expert brainly.com
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SOLVED
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katieb
  • katieb
I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!
anonymous
  • anonymous
\[(2-3i)(3-i)-(4-i)(4+i)\]
anonymous
  • anonymous
(2-3i)(3-i)-(4-i)(4+i)
anonymous
  • anonymous
theres supposed to be one more parenthases after 3i

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More answers

anonymous
  • anonymous
am i foiling this or is that not the right way to go about this problem?
jim_thompson5910
  • jim_thompson5910
you can FOIL or use the table like last time. Which option works best for you?
anonymous
  • anonymous
foil the table is a little confusing.
jim_thompson5910
  • jim_thompson5910
ok what do you get when you FOIL (2-3i)(3-i)
bradely
  • bradely
(2 -3i)(3-i)-(4-i)(4+i) (2)(3-i)-(3i)(3-i)-(4^2-i^2) Multiply find the value Note i^2 = -1 Source: mathskey.com
anonymous
  • anonymous
3-11i
jim_thompson5910
  • jim_thompson5910
correct
jim_thompson5910
  • jim_thompson5910
how about `(4-i)(4+i)` ?
anonymous
  • anonymous
that is 15
anonymous
  • anonymous
brb
jim_thompson5910
  • jim_thompson5910
not 15, but you are close
jim_thompson5910
  • jim_thompson5910
try again
anonymous
  • anonymous
okay
anonymous
  • anonymous
where did i go wrong with my problem i will show you my work.
bradely
  • bradely
(4-i)(4+i) (a-b)(a+b) =a^2-b^2 4^2 -i^2 16-(-1)=17
anonymous
  • anonymous
could the answer be 187i+51?
anonymous
  • anonymous
|dw:1441072256502:dw|
jim_thompson5910
  • jim_thompson5910
i^2 is -1 so \(\Large 16-\color{red}{i^2}\) turns into \(\Large 16-\color{red}{(-1)}\)
anonymous
  • anonymous
im not sure @sayomi
jim_thompson5910
  • jim_thompson5910
Do you see what I mean @huntergirl1 ?
anonymous
  • anonymous
yes now i do @jim_thompson5910
jim_thompson5910
  • jim_thompson5910
ok great, so 16-(-1) = 16+1 = 17 --------------------- \[\large \color{red}{(2-3i)(3-i)}-\color{blue}{(4-i)(4+i)} =\color{red}{3-11i}-\color{blue}{17} = -14-11i\]
anonymous
  • anonymous
@sayomi you were correct and yes @jim_thompson5910 i do understand
jim_thompson5910
  • jim_thompson5910
I'm glad it's making sense
anonymous
  • anonymous
so the ending result is 51-187i
anonymous
  • anonymous
okay do you wnt me to start a new window for the next problem? or to place it here?
jim_thompson5910
  • jim_thompson5910
how are you getting `51-187i` ?
jim_thompson5910
  • jim_thompson5910
I wrote the answer above
anonymous
  • anonymous
bc you put 17 back into the problem
jim_thompson5910
  • jim_thompson5910
are you saying that they wanted you to multiply `(2-3i)(3-i)` and `(4-i)(4+i)` ??
anonymous
  • anonymous
actually i put those answers both into the website they were both incorrect
anonymous
  • anonymous
hwy was the answer supposed to be -14-11i?
anonymous
  • anonymous
why
jim_thompson5910
  • jim_thompson5910
because the 3 and -17 combine to -14
jim_thompson5910
  • jim_thompson5910
(3-11i) - (17) = 3-11i - 17 = (3-17) + (-11i) = -14 - 11i
anonymous
  • anonymous
oh okay.
anonymous
  • anonymous
will you be on to check a few more problems before I submit them?
jim_thompson5910
  • jim_thompson5910
sure
anonymous
  • anonymous
thank you!!!!!!!!!!!!
jim_thompson5910
  • jim_thompson5910
no problem
anonymous
  • anonymous
okay i have one to check its similar to the last problem
anonymous
  • anonymous
|dw:1441074082197:dw|
anonymous
  • anonymous
what did i do wrong?
jim_thompson5910
  • jim_thompson5910
you didn't foil correctly
anonymous
  • anonymous
okay i guess the sqrt part mixed me up
anonymous
  • anonymous
i also tried the box method too
jim_thompson5910
  • jim_thompson5910
|dw:1441074547608:dw|
jim_thompson5910
  • jim_thompson5910
what we do is make a 2x2 box 2 rows and 2 columns the terms of each factor will go along the outside like this |dw:1441074595637:dw|
jim_thompson5910
  • jim_thompson5910
agreed so far?
anonymous
  • anonymous
okay thats how i started it on my paper too
jim_thompson5910
  • jim_thompson5910
ok go ahead and fill it out
anonymous
  • anonymous
|dw:1441074610390:dw|
jim_thompson5910
  • jim_thompson5910
-4 times \(\large -i\sqrt{2}\) should be \(\large +4i\sqrt{2}\) the two negatives cancel |dw:1441074917203:dw|
anonymous
  • anonymous
right?
jim_thompson5910
  • jim_thompson5910
same with the -i and -i being multiplied in the lower right box |dw:1441074956036:dw|
anonymous
  • anonymous
so instead of a negative is a possitive
jim_thompson5910
  • jim_thompson5910
so after filling the boxes and simplifying the expressions in each box, we end up with |dw:1441075014939:dw| since \[\Large i^2*\sqrt{4} = -1*2 = -2\]
anonymous
  • anonymous
okay
anonymous
  • anonymous
so is the answer 18 instead?
anonymous
  • anonymous
no :( dang it please help me i have until 11:50 to submit these
jim_thompson5910
  • jim_thompson5910
now add up the terms inside the boxes \[\Large 16 + 4i\sqrt{2} + 4i\sqrt{2}+(-2) = 14+8i\sqrt{2}\]
jim_thompson5910
  • jim_thompson5910
|dw:1441075415932:dw|
anonymous
  • anonymous
okay that makes since
jim_thompson5910
  • jim_thompson5910
|dw:1441075435745:dw|
anonymous
  • anonymous
okay no do i leave it as 14-8i√2
jim_thompson5910
  • jim_thompson5910
+8i not -8i
jim_thompson5910
  • jim_thompson5910
\[\Large 14 + 8i\sqrt{2}\] is as simplified as it gets
anonymous
  • anonymous
bc the sqrt of 2 cant be any other number? oh okay so possitive 8i
anonymous
  • anonymous
okay thats what i thought
anonymous
  • anonymous
okay so im just going to bed im to tired to work on these i have to be up @ 5 thank you for your help (:
jim_thompson5910
  • jim_thompson5910
you're welcome, glad to be of help

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