Solve the following quadratic equation: z^2+4z+(4+2i)=0?

It’s a question from a-level maths Complex Numbers chapter.

Top 2 Answers

A few days ago

Anonymous

Favorite Answer

z^2+4z+4 = -2i

(z+2)^2 = -2i

z = -2 ± √-2i = -2 ± √2√-i………….(*)

now, in the complex plane,

-i is at an angle 3π/2

√-i will be at angle 3π/4

√-i = cos3π/4 + isin3π/4 = (-1 + i) /√2

substitute this in (*) gives

z = -2 ± √2√-i = -2 ± (-1 + i) = -1- i and -3 + i

A few days ago

Anonymous

two solutions

z = -1-i

and z = -3+i

solve the same way you would any other quadratic equation:

factor, complete the square, or use the quadratic formula.

surely you don’t need me to show you the tedious steps

what with you being an a-level maths student

(actually I used a different method to quickly find the solution)

Can anyone give me some anecdotes………………?

if there were a symbol describing wat he believed in wat would i be??help…?

I need some help with high school physics?

Algebra review help!!!?

Speech Topic help for public speaking class?

can anyone help with math question?

what countries boarder Spain? answer correctly please this is for school.?