Friday, July 19, 2013

find real numbers x and y if: (x+i)(3-iy)= 1+13i

(x+i)(3-iy)= 1+13i 
(3x+y)+(3-xy)i=1+13i 

(1) 3x+y=1, 
(2) 3-xy=13 
(2) 3-xy=13, xy=-10, y=-10/x 

(1) 3x+y=1, 3x+(-10/x)=1, 3x^2-x-10=0, x=2, x=-5/3 

then 
(x,y)=(2,-5) 
or 

(x,y)=(-5/3, 6)

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