May 10: Finding Complex Roots of a Polynomial
Post date: May 10, 2013 9:14:05 PM
Notes:
Given the real root of x^3-1x^2-7x+15 is -3, what are the imaginary roots?
1) use synthetic division to find the trinomial
-3I 1 -1 -7 15
-3 12 -15 x^2-4x+5
1 -4 5 0
2) Use the Quadratic formula to solve for the other two roots
4+/-sqrt(-4^2-4(5)(1)) = 4+/-sqrt(16-20) = 4+/-sqrt(-4) = 4+/-2i = 2+i or 2-i
2(1) 2 2 2
Homework:
Continue working on Polynomial Review Packet
TEST ON THURSDAY 5/16