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Mathematics 12 Online
OpenStudy (anonymous):

.....

OpenStudy (anonymous):

find the real values of x and y for which the complex numbers-3 +ix^2y and x^2+y+4i are conjugate of each other

OpenStudy (ikram002p):

Hint :- consider two equation \(-3+i x^2y=x^2+y-4i\) \(x^2+y+4i=-3-ix^2y\)

OpenStudy (anonymous):

They are the same thing

ganeshie8 (ganeshie8):

I think there was a typo in the question http://www.wolframalpha.com/input/?i=solve+x%5E2%2By%3D-3%2C+x%5E2y%3D-4+in+reals

OpenStudy (ikram002p):

also u can do this trick (i still don't know which one will solve it lol ) \((-3 +ix^2y)(x^2+y+4i )= (9-x^4y^2)=((x^2+y)^2-16))\)

ganeshie8 (ganeshie8):

what are the options @No.name

OpenStudy (anonymous):

No options given but the answer is x=1, y= -4 x=-1 y=-4

OpenStudy (ikram002p):

\(−3+ix^2y=x^2+y−4i \) means that \(x^2+y=-3\) \(x^2y=-4\)

OpenStudy (ikram002p):

for \(x^2y=-4\) since you wanna real then \(x =2,\sqrt2 ,1\) y=-1,-2,-4 try to find wich pair satisfy first equation \((2,-1) (\sqrt 2 , -2) (1,-4) \)

OpenStudy (anonymous):

so basically is it trial and error

OpenStudy (ikram002p):

also take negative side , it works

OpenStudy (ikram002p):

basicly you need to know the proposition if C1,c2 both complex number \(C_1=x_1+iy_1\) \(C_2=x_2+iy_2\) then \(C_1 = C_2\iff x_1=x_2 \text{ and } y_1=y_2\)

OpenStudy (ikram002p):

and you need to know how to construct conjugate of complex number ..

OpenStudy (anonymous):

x^2 y = -4 x^2 +y = -3 I got these two equations then what i should do

OpenStudy (ikram002p):

ok , when you got x^2 y = -4 factorize -4

OpenStudy (ikram002p):

or solve like equation x^2=-3-y and x^2=-4/y

ganeshie8 (ganeshie8):

or you can solve them by substitution : x^2y = -4 y = -4/x^2 substitute this in second equation and solve x

OpenStudy (anonymous):

Yessssss , got the answer , couldn't reply because of slow internet

OpenStudy (anonymous):

In the second equation we would have to substitute that then again substitute x^2 with a variable

ganeshie8 (ganeshie8):

exactly ! x^2 +y = -3 x^2 -4/x^2 = -3 t^2 +3t - 4 = 0 (t+4)(t-1) = 0 t = 1 or -4 discard -4

OpenStudy (anonymous):

Even i substituted the same variable "t" (although it dosen't matter) hehe gone are the days to substitute x's and y's

ganeshie8 (ganeshie8):

haha! so basically two complex numbers equal IF AND ONLY IF their real parts are equal, and their imaginary parts are equal

ganeshie8 (ganeshie8):

i think @ikram002p said that earlier..

OpenStudy (anonymous):

yes

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