How many complex number that satisfies the equation below?
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
∣ z ∣ ( z − 4 − i ) + 2 i = ( 5 − i ) z ⇔ z ( ∣ z ∣ − 5 + i ) = 4 ∣ z ∣ + ( ∣ z ∣ − 2 ) i
Take the modulus of both sides, we get:
∣ z ∣ ( ∣ z ∣ − 5 ) 2 + 1 = ( 4 ∣ z ∣ ) 2 + ( ∣ z ∣ − 2 ) 2
Make the substitution t = ∣ z ∣ , the above equation becomes:
t ( t − 5 ) 2 + 1 = ( 4 t ) 2 = ( t − 2 ) 2 ⇔ ( t − 1 ) ( t 3 − 9 t 2 + 4 ) = 0
That cubic equation has 3 distinct roots t ≥ 0 , so there are 3 complex numbers z that satisfies the equation