Complex question (1 Viewer)

synthesisFR · Jul 31, 2023

do we need to know how to solve this stuff
sorry fi its a dumb question
my teacher told me to ignore these sort of q's

synthesisFR · Jul 31, 2023

dingd0ng said:
we are doing this in yr 10 lmao

thats nice but does the mx2 syllabys require us to learn these?
ive never seen it in a past hsc exam

unofficiallyred12 · Jul 31, 2023

synthesisFR said:
View attachment 39113
do we need to know how to solve this stuff
sorry fi its a dumb question
my teacher told me to ignore these sort of q's

it definitely could come up in a test, just a bit of a trek tbh

unofficiallyred12 · Jul 31, 2023

also u can just get a^2 + b^2 by using |a+ib|^2 lol

carrotsss · Jul 31, 2023

Yeah it’s in the syllabus imo, it’s obviously a pretty big question but achievable if you just follow logical steps

synthesisFR · Jul 31, 2023

carrotsss said:
Yeah it’s in the syllabus imo, it’s obviously a pretty big question but achievable if you just follow logical steps

this is the method u would use?

mmmmmmmmaaaaaaa · Jul 31, 2023

synthesisFR said:
View attachment 39113
do we need to know how to solve this stuff
sorry fi its a dumb question
my teacher told me to ignore these sort of q's

synthesisFR said:
this is the method u would use?

Yes I would

carrotsss · Jul 31, 2023

synthesisFR said:
this is the method u would use?

i mean something like that, quadratic formula is a pain for this question (possible, but annoying) so it seems like the best method

tywebb · Jul 31, 2023

synthesisFR said:
ignore these sort of q's

Don't ignore it. It has already been in HSC exams for the current syllabus. These might be easier than the one you put, but the method is similar.

2020 HSC Q11e

2021 HSC Q11d

SadCeliac · Jul 31, 2023

synthesisFR said:
View attachment 39113
do we need to know how to solve this stuff
sorry fi its a dumb question
my teacher told me to ignore these sort of q's

Am I blind? What was the initial question? Solve for x??

carrotsss · Jul 31, 2023

tywebb said:
Don't ignore it. It has already been in HSC exams for the current syllabus. These might be easier than the one you put, but the method is similar.

2020 HSC Q11e

View attachment 39115
2021 HSC Q11d

View attachment 39116

Yeah it’s in the syllabus here:

synthesisFR · Jul 31, 2023

tywebb said:
Don't ignore it. It has already been in HSC exams for the current syllabus. These might be easier than the one you put, but the method is similar.

2020 HSC Q11e

View attachment 39115
2021 HSC Q11d

View attachment 39116

ah okay thanks
the one i put was so disgusting i was just thinking of it as a diff type of quadratic q lol

tywebb · Jul 31, 2023

I did your question and got almost the same answer. I think you missed an i at the end. I used a slightly different method.

$ix^2+3x-4=0\therefore x=\textstyle\frac{-3\pm\sqrt{3^2-4i(-4)}}{2i}=\frac{-3\pm\sqrt{9+16i}}{2i}$

$\text{Suppose }\sqrt{9+16i}=a+bi\text{ for some real numbers }a,b.$

$\text{Then }9+16i=a^2-b^2+2abi$

$\text{Equating real and imaginary parts, }a^2-b^2=9\text{ and }2ab=16$

$\text{ and so }b=\textstyle\frac{8}{a}\ \therefore a\text{ and }b\text{ have the same sign}.$

$\text{Solving simultaneously for }a,b,\text{ and first substituting }b=\textstyle\frac{8}{a}$

$\begin{aligned}\textstyle a^2-\frac{64}{a^2}&=9\\a^4-64&=9a^2\\a^4-9a^2-64&=0\\a^2&=\textstyle\frac{9\pm\sqrt{9^2-4(1)(-64)}}{2}\\&=\textstyle\frac{9+\sqrt{337}}{2}\text{ rejecting }-\text{because for real }a,\ a^2\ge0\end{aligned}$

$b^2=\textstyle a^2-9=\frac{9+\sqrt{337}}{2}-9=\frac{-9+\sqrt{337}}{2}$

$\text{Hence }a=\textstyle\pm\sqrt{\frac{9+\sqrt{337}}{2}}, b=\pm\sqrt{\frac{-9+\sqrt{337}}{2}}\text{ respectively and so}$

$\begin{aligned}x&=\textstyle\frac{-3\pm\left(\sqrt{ \frac{9+\sqrt{337}}{2}}+i\sqrt{\frac{-9+\sqrt{337}}{2}}\right)}{2i}\\ &=\textstyle\pm\frac{1}{2}\left(\sqrt{ \frac{-9+\sqrt{337}}{2}}-i\sqrt{\frac{9+\sqrt{337}}{2}}\right)+\frac{3i}{2}\end{aligned}$

carrotsss · Jul 31, 2023

tywebb said:
I did your question and got almost the same answer. I think you missed an i at the end. I used a slightly different method.
View attachment 39120

I’m so sorry but wtf are your 8s lmaooo that looks like a gamma symbol

tywebb · Jul 31, 2023

carrotsss said:
I’m so sorry but wtf are your 8s lmaooo that looks like a gamma symbol

8’s. Maybe I’ll type it neater tomorrow.

EDIT: I typed it to make it neater now.

carrotsss · Jul 31, 2023

tywebb said:
8’s. Maybe I’ll type it neater tomorrow.

Nah it’s all good I just thought it was funny

SadCeliac · Jul 31, 2023

carrotsss said:
I’m so sorry but wtf are your 8s lmaooo that looks like a gamma symbol

Pov: mx2 students training to become med students and doctors

synthesisFR · Jul 31, 2023

Screen Shot 2023-07-31 at 9.57.16 pm.png

Screen Shot 2023-07-31 at 9.57.36 pm.png

Screen Shot 2023-07-31 at 9.57.46 pm.png

am i supposed to do it the long way or am i allowed to memorise the formulas and just apply it?

synthesisFR · Jul 31, 2023

wait why do i have no idea wtf is going one someone pls help idk why im struggling with this all of a sudden

SadCeliac · Jul 31, 2023

synthesisFR said:
wait why do i have no idea wtf is going one someone pls help idk why im struggling with this all of a sudden

which part are you struggling with / which question - sorry, there's like five attachments on this thread

Complex question (1 Viewer)

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