Advanced Functions 3.3 Zeros – 3.4 Fundamental Theorem of Algebra Name _______________________________ Date _____________ Period ________ Solutions = Roots = Zeros = x-intercepts Example 1: Determine whether 2 is a root of: x4 – 4x3 – x2 + 4x = 0 f(2) = _______________________________ so 0 (zero) is / is not Example 2: Determine whether 7 is a root of: x3 + 4x2 – 47x – 210 = 0 a root of the equation. (Use synthetic division!) Make 3 statements about Example 2. 1. 2. 3. Example 3: Write the polynomial of least degree whose roots are: –7i, 7i, 4 and –4. Example 4: Solve (x + 3)(x2 – 16) = 0 and graph the related polynomial function. Zeros of a Polynomial Function Note: ALL polynomial functions have graphs that are _____________________________________ . Multiple Zeros of a Polynomial Function: If P(x) has (x - r) as a factor exactly k times, then r is a zero of P(x) of multiplicity k. Example 5: Find the zeros of P(x) and state the multiplicity of each zero. P(x) = (x – 2)2(x + 4)6(x – 8)8(3x+7) ______ occurs as a zero of multiplicity ______. ______ occurs as a zero of multiplicity ______. ______ occurs as a zero of multiplicity ______. ______ occurs as a zero of multiplicity ______. Note: Simple Zero: _____________________________________________________________ Fundamental Theorem of Algebra Every polynomial equation with degree greater than zero has at least one root in the set of complex numbers. The degree of a polynomial indicates _______________________________________________ . Every polynomial of degree n (n>0) can be written as ___________________________________ ______________________________________________________________________________ . P(x) = A polynomial equation of degree n has exactly _____ complex roots. Example 6: State the number of complex roots of each equation. Then, find the roots and graph the related function. a) 2x3 – 18x = 0 b) (x+4)(x–2)(x–6)(x+6) = 0 The Rational Zero Theorem: It is important because it enables us to narrow the search for rational zeros to a finite list. If P(x) = anxn + an-1xn-1 + an-2xn-2 + … + a1x1 + a0 has integer coefficients ( an 0 ) p and is a rational zero (in lowest terms) of P, then q p is a factor of the constant term a0 and q is a factor of the leading coefficient an . Example 8: Find the roots of: x3 + 6x2 + 10x + 3 = 0 Hint: Apply the Rational Zero Theorem to find the possible rational roots! Hint: Use synthetic division to locate a root! Upper and Lower Bound Theorem: Let P(x) be a polynomial function with real coefficients. Use synthetic division to divide P(x) by (x – b), where b is a nonzero real number. Upper Bound: (Def: No zero is greater than b.) a) if b > 0 and the leading coefficient of P is positive, then none of the numbers in the bottom row of synthetic division are negative! b) if b > 0 and the leading coefficient of P is negative, then none of the numbers in the bottom row of synthetic division are positive! Lower Bound: (Def: No zero is less than b.) a) if b < 0 and the numbers in the bottom row of synthetic division alternate in sign! Note: the number “0” can be considered positive or negative as needed to produce an alternating sign pattern. Example 9: Use the Upper- and Lower-Bound Theorem to locate the smallest positive integer that is an upper-bound and the largest negative integer that is a lower-bound of the real zeros of P(x) = 2x3 + 7x2 – 4x – 14 Hint: Apply the Rational Root Theorem to find the possible rational roots! Hint: For the Upper-bound, try x = 1, x = 2, … Hint: For the Lower-Bound, try x = –1, x = –2, … Zero Location Theorem: Let P(x) be a polynomial function and let a and b be two distinct real numbers. If P(a) and P(b) have opposite signs, then there is at least one real number c between a and b such that P(c) = 0. Example 10: Use the Zero Location Theorem to state between which two consecutive integers the real zeros of P(x) = 2x3 + 7x2 – 4x – 14 are located. x y Real Zeros occur between _______ and _________ Real Zeros occur between _______ and _________ Real Zeros occur between _______ and _________ Use the calculator to locate the zeros of P(x) = 2x3 + 7x2 – 4x – 14 Sketch the graph below. to the nearest tenth. HW: p. 316-317 #1-4, 7-10, 17, 22, (37-39, 50-51 show synthetic) p. 327 # 1-2, 11-19 odd, 31-34 *** Test Chapter 3.1- 3.4 in 2 classes (Nov15-16)