9.2 Solving Quadratics by Completing the Square.notebook March 08, 2016
March 8thQuiz on Friday
Due Next Class: 9.2 HW & Video Notes
Get Ready:
Unit 9: Quadratic Functions
Lesson 9.2 Solving Quadratic Equations that are Unfactorable...or too difficult to factor
1) What does it mean to solve the equation x2 + 5x 14 = 0 ?
2) Solve the following equations.
Hint: How can you check if your solution(s) is correct?
a. 5n2 + 14n + 3 = 6n + 4n2 4 b. x2 2x = 12
9.2 Solving Quadratics by Completing the Square.notebook March 08, 2016
Mathematical Magic
How can we use that to solve (x+4)2 = 25
What number multiplied by itself equals 25?
Conclusion: If we take the square root of a number, then...
Solve: (x 3)2 = 49
9.2 Solving Quadratics by Completing the Square.notebook March 08, 2016
How to Solve Unfactorable Quadratic Equations
Could we get x2 2x = 12 to look like (x1)2 = 13 so we can solve it?
Is (x1)2 = 13 a quadratic equation?
9.2 Solving Quadratics by Completing the Square.notebook March 08, 2016
Steps for Solving Unfactorable Quadratic Equations
Completing the Square
1) Divide everything by a (the coefficient of x2)
2) Move the constant term to the right side of the equation
3) Divide b (the coefficient of x) by 2 and then square it
4) Add that square number to each side of the equation
5) Factor the quadratic trinomial on the left side of the equation Should factor a perfect square trinomial
6) Solve for x
9.2 Solving Quadratics by Completing the Square.notebook March 08, 2016
x2 2x = 12
Completing the Square
1) Divide everything by a (the coefficient of x2)
2) Move the constant term to the right side of the equation
3) Divide b (the coefficient of x) by 2 and then square it
4) Add that square number to each side of the equation
5) Factor the quadratic trinomial on the left side of the equation Should factor to a perfect square trinomial
6) Solve for x
3) b = 2
2= =
4) x2 2x + = 12 +
x2 2x 12 = 0