Core Connections Integrated III, 2015
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Core Connections Integrated III, 2015 View details
1. Section 9.1
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Exercise 17 Page 438

Use the factorization of the given polynomial and the Zero Product Property.

2, -5i, 5i

Practice makes perfect

We want to solve the equation in the form of P(x)=0, where P(x) is a polynomial function. This means that we want to find zeros of P(x). P(x) = x^3-2x^2+25x-50=0 We also know that the quotient of P(x) and x-2 equals x^2 + 25. This means that x-2 multiplied by x^2 + 25 gives P(x). (x^3 - 2x^2 + 25x -50) ÷ (x-2) = x^2+25 ⇕ x^3 - 2x^2 + 25x -50 = (x-2)(x^2 + 25) The degree of P(x) is 3, so we know by the Fundamental Theorem of Algebra that the polynomial has exactly 3 roots. Let's use the Zero Product Property to find them! (x-2) (x^2 + 25) = 0 ⇕ x-2 = 0 or x^2 + 25 = 0 The first factor is equal to zero when x = 2. Let's move on to factoring the second expression.

x^2 + 25 = 0

a^2+b^2=(a+bi)(a-bi)

(x+5i)(x-5i) = 0

Now we can use the Zero Product Property again. (x+5i)(x-5i) = 0 ⇕ x + 5i = 0 or x - 5i = 0 The polynomial x^2 + 25 has 2 complex roots, -5i and 5i. Finally, let's list the roots of P(x). 2, -5i, 5i