Solve by taking roots.

21. ( 2) 2 18x

2or 6x x

Warm up

Homework Review

Skills Check

CCGPS GeometryDay 52 (1-29-14)

UNIT QUESTION: How are real life scenarios represented by quadratic functions?

Today’s Question:When is it useful to solve quadratics by completing the square?Standard: MCC9-12..A.REI.4b

Completing the Square

• Completing the square is used for all those problems that don’t factor!!

• It is used to solve these equations for the variable.

• It gets a little messy when a is not 1.

Completing the Square

ax2 + bx + c = 0

Is another way to solve a quadratic equation.

a needs to be 1.c needs to be moved to

the other side of the = sign

Steps to Completing the Square

1. Move the constant to the other side.

2. Add to BOTH sides of the eqn.3. Factor!

4. Take the square root of both sides.5. Solve for x.

2

2b

Example 1:

2 10 54 0x x

5 29x i

Example 2:

2 18 85 0x x

9 2x i

Example 3:

2 20 73 0x x

10 173x

Example 4:

2 6 90 8x x

3 73x i

Example 5:

2 10 56 6x x

5 87x

Example 6:

2 14 75 8x x

7 34x i

Worksheet10 problems