Harap tolong : Kaunter pertanyaan Matematik Basic aku..

peace

Aku ni bodo sket sekolah dulu... so dah tua-tua ni aku nak tanya kat sini banyak soalan..

soalan pertma :


32 = r^4 - r^2


cemana nak cari value R?

Soklan nie ade kaitan ngan indeks form 4 tu kot?

Thanks...

kat sini.. aku simbolkan r^2 dengan r2 kay..

r4-r2-32=0

let x=r2

x2-x-32=0

guna formula nih tuk cari x,
x= (-b+/-b2-4ac)/2a

then, substitute balik x dlm r.. cari sendiri hahah..

orang_awam

kalau aku yg malas nak derive equation ni, aku pakai "Goal Seek" je dlm Excel.

kenapa perlu nak ganti variable r dgn x? tak biasa guna r sbg variable?

tak silap aku kau log10 kan je dua2 belah.

peace

Thanks Ronaldinho,

tapi aku masih tak faham..

Kenapa

R^4 - R^2 - 32 = 0

dia jadi

R^2 - R - 32 = 0 ?

walau nak tukar jadi Quadratic, tapi memang  R^4 - R^2 = R^2 ke?



Orang_Awam,

Kenapa nak kena log10 dedua belah?




sorry, sekolah dulu ak mmg bodo matematik....

BarcaFan

Originally posted by peace at 2-8-2006 12:14 AM


Kenapa

R^4 - R^2 - 32 = 0

dia jadi

R^2 - R - 32 = 0 ?


Orang_ ...

actually, dari R^4 - R^2 - 32 = 0,jadi ( R^2 )^2- R^2 - 32 = 0

replace R^2 = x untuk dapat bentuk quadratik...

x^2-x-32=0

then punch in value into calculator,

x = 6.18 and -5.18

so, R^2 = x = 6.18 and -5.18

R= ?

MACD

Wow you guys are brilliant.

As mentioned earlier by orang_Awam, you can also solve quadratic equation using Excel.

http://www.bettersolutions.com/excel/EAV113/LT721811311.htm

aku_EnSeM

dah pong kene jawab....

Originally posted by BarcaFan at 2-8-2006 12:32 AM


actually, dari R^4 - R^2 - 32 = 0,jadi ( R^2 )^2- R^2 - 32 = 0

replace R^2 = x untuk dapat bentuk quadratik...

x^2-x-32=0

then punch in value into calculator,

x = 6.18 and -5.18

...

ha.. betul tu... so, R =sqrt(6.18) = 2.4859

rudz

Originally posted by orang_awam at 1-8-2006 10:57 PM
kalau aku yg malas nak derive equation ni, aku pakai "Goal Seek" je dlm Excel.

kenapa perlu nak ganti variable r dgn x? tak biasa guna r sbg variable?

tak silap aku kau log10 kan je ...

emm... nak lagik cantik ekau log r kan je

orang_awam

Originally posted by peace at 2-8-2006 12:14 AM
Orang_Awam,

Kenapa nak kena log10 dedua belah?

sebab kalau log10 kan r^4 jadi 4 x log10 r
so senang sikit nak jadikan r tajuk equation tu.

cer selesaikan dgn log, sama dak nilai r..

sedondon

tak suka calculus

i bagi yang cari simple sikit

32 = r^4-r^2
so
r^4-r^2-32 =0
let r^2=x
hence
x^2-x-32=0
Quadratic eq:
x=6.1789 , x= -5.1789 (ignore)
Since r^2 = x =6.1789
hence r = +- 2.4857

is it wat u want?

kite x leh log kan ke dua2 belah..sbb bile log r^4 - r^2 kite xleh ceraikan jd log r^4 - log r^2..operasi tambah tolak x leh selesaikan dgn cara log melaikan drb n bahagi...betul x????

aku_EnSeM

calculus best...

banyak graf yg pusing2... pastu kepale pong pusing2.. :gila: