SOLUTION: I was just wondering if I could get help on these questions i'm a bit confused, part (a) is more clear to me then part (b) however so I feel im close to solving part (a) im just un

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: I was just wondering if I could get help on these questions i'm a bit confused, part (a) is more clear to me then part (b) however so I feel im close to solving part (a) im just un      Log On


   



Question 863182: I was just wondering if I could get help on these questions i'm a bit confused, part (a) is more clear to me then part (b) however so I feel im close to solving part (a) im just unsure if it's correct
(a) Find all the roots of p(z)=z3 −5z2 +11z−15, given that 1 − 2i is a root.
(b) Find all solutions of z for z^2 +4z ̄+4=0 where z∈C.

Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
question a seems more complicated than question b. I'm assuming you meant to indicate exponents in question a, as z%5E3-5z%5E2%2B11z-15. Your two complex roots with imaginary components are 1-2i and 1+2i. Each of these gives a factor which can be multiplied to give a quadratic factor for p(z). Polynomial division will give you the other needed factor of p(z). If you need no help with that and can understand the process, then you would not likely have any confusion about question b...


Question b:
There is a stray mark above the plus sign, but as the quadratic equation which this appears to be, find z using factorization.
z%5E2%2B4z%2B4=%28z%2B2%29%5E2=0.
highlight%28z=-2%29.
Yes negative 2 IS a complex number. It is also a real number. You can express it as highlight%28-2-0%2Ai%29 and highlight%28-2%2B0%2Ai%29.