
Lance P. answered 10/19/19
SWAG--UM (Students Will Achieve Greatness & Understanding in Math)
F√ind a polynomial function of lowest degree with rational coefficients that has the given numbers as zeros:
(2-√3), (1+i)
***Important*** Complex numbers always, I repeat always come in conjugate pairs!
Recall complex number form as a + bi and its conjugate a - bi, this is very important to rewrite/convert complex zeros back into their factored form, based on this information, I know that the polynomial will be at minimal a degree three function (cubic equation).
Recall the the general pattern for and degree polynomial, such as:
y = a (x - r,)n (x - r2)n, where n represents the multiplicity of the factor.
Step 1) We convert and rewrite zeroes into the factored form and we will start with the easier of the two:
2-√3, setting it equalled to x as follows:
x = 2 - √3 → Using algebra we manipulate it to set it zero (x - 2 +√3)=0
Step 2) Find the conjugate of the given complex zero: 1 + i, which is 1 - i
Step 3) Set both complex zeros equal to zero and rewrite/convert back to factored form:
x = 1+i and x = 1 - i → Using algebra to manipulate we get: (x - 1 - i) = 0 and (x - 1 + i) = 0
Step 4) We multiply together these two complex factors using FOIL/distribution to eliminate the i generating a quadratic expressions as follows:
(x - 1 - i)(x - 1 + i) → After FOIL and eliminating i, we get: x2- 2x + 2
Step 5) Combine factors and plug them into the general polynomial factor form as:
y = a (x - 2 +√3) (x2- 2x + 2), we need a point (x,y) that lies on this polynomial in order to find a, the leading coefficient of the function.