0
Wed 12/2 Lesson 5 – 5 Learning Objective: To apply Rational Root Thm (& Descartes’Rule) Hw: W.S. 5-5
Algebra II
To understand & apply the Rational Root Theorem To understand & apply the Conjugate Root Theorem (To understand and apply Descartes’ Rule of Signs)
Look at COEFFICIENTS
q = 1 p = 12
q = 3 p = 10 Divide each numerator by each denominator
q = 1 p = 42
Step 2: Test each possible rational root in original function until you find a root. Do synthetic substitution until get R0
1 Nope! 1 is NOT a root! Try something else!
2 YES! 2 IS a root!
q = 2 p = 6
YES! -1 IS a root!
2 Sign Change 1 Sign Change Sum = 3
5 Sign Change 4 Sign Change
It could have 5 positive roots, 4 negative roots, & 0 imaginary roots It could have 3 positive roots, 2 negative roots, & 4 imaginary roots
3 Sign Change 1 Sign Change It could have 3 + roots, 1 - root, & 0 imaginary roots It could have 1 + roots, 1 - root, & 2 imaginary roots
q = 1 p = 6
1 YES! 1 IS a root!