complex no. question (1 Viewer)

[Gruma]

This question is from the cambridge book but i cant seem to get the same answer as them, and bacause the solutions arnt worked at all........ i though i someone might be able to shed some light on it.

solve. x^2 + (2 - i)x - 2i = 0





(its question 4(b) in the diagnostic test 2)

 

[Harimau]

x^2 + (2 - i)x - 2i = 0

(x+2)(x-i)=0

Therefore, x=-2 or x=i

If the question mentioned that X is an element of real numbers, then only take the x= -2.

 

[PG5]

hmm... yeah that works

expand then factorize
x^2 + 2x - ix - 2i = 0
(x + 2)(x - i) = 0

what Harimau said..

 

[Gruma]

thanx man.

i think ive been studying 2 hard, if im forgettin easy shit like this.

 

[Jeo]

yeah that happens to me...

actually, I just use it as an excuse

 

[bobo123]

if the question isnt as neat as this one, you could always muscle them out with quadratic formula

 

[ND]

Originally posted by bobo123
if the question isnt as neat as this one, you could always muscle them out with quadratic formula

Yeh but that can get messy. There is a method that i like that involves the discriminant.

 

[Gruma]

yeah thats what stuffed me up. i kept tryin to make the question 2 hard by doin quadratic formula and squaring the discriminant and all those methods, whan all i realy needed 2 do was simple.

 

[Jeo]

i kept tryin to make the question 2 hard

We dun need that in 4U now do we?