Find the absolute values of z if 2z-i +5 = 3z -3i +1

3 Answers | Add Yours

justaguide's profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

We have to find the absolute value of z given that 2z-i +5 = 3z -3i +1

2z - i + 5 = 3z -3i +1

=> 3z - 2z = -i + 3i + 5 -1

=> z = 2i + 4

The absolute value of z is given by sqrt ( 2^2 + 4^2)

=> sqrt ( 4 + 16)

=> sqrt 20

Therefore the absolute value of z is sqrt 20.

hala718's profile pic

hala718 | High School Teacher | (Level 1) Educator Emeritus

Posted on

Given the complex equation:

2z -i + 5 = 3z -3i +1

We need to find the absolute value of z.

First we need to rewrite z into the format of the complex number z = a+bi

let us combine terms with z on the left side.

==> 2z -3z = -3i +1 +i -5

==> -z = -4 -2i

Now we will multiply by -1

==> z = 4 + 2i

Now we will calculate the absolute values.

==> l z l = sqrt(a^2 + b^2)

               = sqrt( 4^2 + 2^2)

               = sqrt(16 + 4) = sqrt20 = 2sqrt5

==> l zl = 2sqrt5

neela's profile pic

neela | High School Teacher | (Level 3) Valedictorian

Posted on

We first solve the equation  2z-i +5 = 3z -3i +1 and then find the absolute value of z.

We subtract 3z from both sides:

2z-i+5-3z = = -3i+1.

-z -i+5 = -3i+1.

We add i-5 to both sides:

-z = -3i+1+i-5

-z = -2i-4.

We multiply both sides by -1.

z = 4+2i.

We know that the absolute vale of z = x+iy = sqrt(x^2+y^2).

Therefore the absolute value of z = (4+2i) is sqrt(4^2+2^2) = sqrt(16+4) = sqrt 20 = 2sqrt5.

Therefore the absolute  value of z = 2sqrt5.

We’ve answered 318,917 questions. We can answer yours, too.

Ask a question