Roots of a squared polynomial ( complex numbers)

In summary, the conversation discusses a problem involving finding the square roots of complex numbers and the confusion surrounding the method of solving it. The person is unsure of what the teacher wants and questions why they have to find the roots of a specific number. The expert explains that (z + 2)2 is not a factor of p(z2) and clarifies the meaning of p(z2). The person thanks the expert for their help and understanding.
  • #1
Axe199
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Homework Statement



problem in a pic attached

Homework Equations





The Attempt at a Solution


i solved i and ii a , when it came to b , i just said that every one of the 3 roots will be squared having 2 roots 1 + and 1 - but then i read the marking schemes ( also attached) , and i got really confused and now i don't know what he wants from me
 

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  • #2
Axe199 said:

Homework Statement



problem in a pic attached

Homework Equations





The Attempt at a Solution


i solved i and ii a , when it came to b , i just said that every one of the 3 roots will be squared having 2 roots 1 + and 1 - but then i read the marking schemes ( also attached) , and i got really confused and now i don't know what he wants from me

He wants you to tell him what are all the square roots of -2, -2+2*sqrt(3)*i and -2 - 2*sqrt(3)*i.
 
  • #3
Ray Vickson said:
He wants you to tell him what are all the square roots of -2, -2+2*sqrt(3)*i and -2 - 2*sqrt(3)*i.

why can't i just say (z+2)^2= 0 and solve and do the same for the complex roots?
why do i have to find the roots of the -2?
 
  • #4
Axe199 said:
why can't i just say (z+2)^2= 0 and solve and do the same for the complex roots?
why do i have to find the roots of the -2?

(z + 2)2 is not a factor of p(z2). It is a factor of (p(z))2, however, a completely different polynomial.
The polynomial is not the object being squared. p(z2) only means that the variable z is being replaced with the variable z2. So, as a result, we know that z2 + 2 is a factor.
 
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  • #5
slider142 said:
(z + 2)2 is not a factor of p(z2). It is a factor of (p(z))2, however, a completely different polynomial.
The polynomial is not the object being squared. p(z2) only means that the variable z is being replaced with the variable z2. So, as a result, we know that z2 + 2 is a factor.
okay...thanks very much, tht was a tricky one, or maybe i am stupid :D
either way , thanks , i got it
 

1. What are the roots of a squared polynomial?

The roots of a squared polynomial are the values of the variable that make the polynomial equal to zero. For example, the roots of the polynomial x^2 + 4x + 4 are -2 and -2, since (-2)^2 + 4(-2) + 4 = 0.

2. Can a squared polynomial have complex roots?

Yes, a squared polynomial can have complex roots. Complex numbers are numbers that include a real part and an imaginary part, such as 3 + 4i. If a polynomial has complex coefficients, it is possible for it to have complex roots as well.

3. How do you find the roots of a squared polynomial with complex numbers?

To find the roots of a squared polynomial with complex numbers, you can use the quadratic formula. The quadratic formula is x = (-b ± √(b^2 - 4ac)) / 2a, where a, b, and c are the coefficients of the polynomial in the form ax^2 + bx + c. The ± sign indicates that there will be two solutions, one with a positive square root and one with a negative square root.

4. What does it mean if the roots of a squared polynomial are imaginary?

If the roots of a squared polynomial are imaginary, it means that the polynomial has no real roots. This can happen when the discriminant (b^2 - 4ac) in the quadratic formula is negative, resulting in a square root of a negative number. Imaginary roots are still valid solutions to the polynomial, but they will be complex numbers.

5. Can a polynomial with real coefficients have complex roots?

Yes, a polynomial with real coefficients can have complex roots. This can happen when the polynomial has a quadratic term with a coefficient that is not a perfect square. For example, the polynomial x^2 + 2x + 5 has complex roots, even though all of its coefficients are real numbers.

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