To calculate: Polynomial equation with real coefficients that has roots

Tashan Flores

Tashan Flores

Answered question

2022-03-03

To calculate: Polynomial equation with real coefficients that has roots 3, 1i.

Answer & Explanation

Ulgelmorgs

Ulgelmorgs

Beginner2022-03-04Added 8 answers

Formula used: (a+b)(ab)=a2b2
Calculation:
If the polynomial has real coefficients, then it's imarginary roots occur in conjugate pairs. So, a polynomial with the given root 1i must have another root as 1+i.
Since each root of the equation corresponds to a factor of the polynomial, also, the roots indicate zeros of that polynomial, thus, the polynomial equation is written as,
(x3)[x(1i)][x(1+i)]=0
(x3)(x1+i)(x1i)=0
Further use arithmetic rule,
(a+b)(ab)=a2b2
Here, a=x1,b=i
Now, the polynomial equation is,
(x3)[(x1)2(i)2]=0
Use arithmetic rule.
(ab)2=a22ab+b2
and i2=1.
Now, the polynomial equation is:
(x3)(x22x+1+1)=0
(x3)(x22x+2)=0
x33x22x2+6x+2x6=0
x35x2+8x6=0
Hence, the polynomial eqquation of given roots 3, 1i is x35x2+8x6=0.
Jeffrey Jordon

Jeffrey Jordon

Expert2022-08-02Added 2605 answers

Answer is given below (on video)

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