PDA

View Full Version : SAT subject Complex zeroes



elizabeth
12-28-2013, 04:38 PM
Complex zeroes Subject test Math level 2
Which of the following is a factor of P(x) given that 1+i is a zero of this polynomial?

(A) 1+i
(B) 1-i
(C) x-(1+i)
(D) x-(1-i)
(E) -1-i

Thanks!

Oliver
12-28-2013, 04:39 PM
Complex roots occur in conjugate pairs which means that if a polynomial with real coefficients has a root of the form a+bi then a-bi is also a root.

Based on the aforementioned theorem we have that the other root is equal to 1-i .

So, the factor that corresponds to this root is x-(1-i)

Therefore the correct answer is (D).

elizabeth
12-28-2013, 04:40 PM
Complex roots occur in conjugate pairs which means that if a polynomial with real coefficients has a root of the form a+bi then a-bi is also a root.

Based on the aforementioned theorem we have that the other root is equal to 1-i .

So, the factor that corresponds to this root is x-(1-i)

Therefore the correct answer is (D).

thanks!!:)