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Lecture 1

MATH 111 Lecture Notes - Lecture 1: Imaginary Number, Quadratic Formula


Department
Mathematics
Course Code
MATH 111
Professor
Tinka Davis
Lecture
1

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8/27/2018
1.4- Quadratic Equations
1. Zero-Product Property (use every time we factor)
If    then a=0 or b=0
Ex. Solve-
(x-5)(x+1)=0
x-5=0 or x+1=0
x=5 x=-1
ex. Solve-  
2x^2-x-3=0 Standard form- everything on one side and 0 on the other
(2x-3)(x+1)=0 Using the guess and check method
     If you get the opposite, switch the signs of the numbers. If you get a
  completely wrong number, switch which parentheses the numbers are in.
Product Using the AC method
-6 2x times -3x should be -6 and 2x+-3x should be -1
2x -3x A=2, B=-1, C=-3
-1
Sum^
      (factor)
Common Common
Factor Factor
2x(x+1) -3(x+1) =0
(x+1)(2x+3)
X+1=0 2x-3=0
X=-1 2x=3
X=3/2
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