5.5 Day 1 Solve by Factoring
December 02, 2008
5­5 Day 1
Solving Quadratic Equations
Objective:
Solve quadratic equations in standard form by factoring.
Nov 30­12:18 PM
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5.5 Day 1 Solve by Factoring
December 02, 2008
Check Skills You'll Need
Factor each expression:
1. x2 + 5x ­ 14
2. 4x2 ­ 12x
3. 9x2 ­ 16
Nov 30­12:22 PM
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5.5 Day 1 Solve by Factoring
December 02, 2008
Remember that a quadratic equation in STANDARD FORM looks like this:
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y = ax + bx + c
So, how do we solve for x?
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Solving for x is finding the x­intercepts. The y­coordinates of the x­intercepts are 0. Therefore, we should set y equal to zero and solve for x.
Nov 30­12:25 PM
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5.5 Day 1 Solve by Factoring
December 02, 2008
y = ax2 + bx + c
Once we factor and set y equal to zero, then what?
TRY ONE!
Nov 30­12:41 PM
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5.5 Day 1 Solve by Factoring
December 02, 2008
Let's solve for x: y = 2x2 ­ 11x + 15 Step 1: Set y equal to zero.
y = 2x2 ­ 11x + 15
0 = 2x2 ­ 11x + 15
Step 2: Factor.
Step 3: Use the zero product rule and solve.
Nov 30­12:35 PM
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5.5 Day 1 Solve by Factoring
December 02, 2008
Solve for x using factoring: x2 + 7x = 18
Hint: Get all the terms on one side so that the other side is zero!
Nov 30­12:46 PM
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5.5 Day 1 Solve by Factoring
December 02, 2008
Solve for x using factoring: 16x2 = 8x
Nov 30­12:49 PM
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5.5 Day 1 Solve by Factoring
December 02, 2008
Solve for x using factoring: 2x2 + 4x = 6
Nov 30­12:49 PM
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5.5 Day 1 Solve by Factoring
December 02, 2008
HOMEWORK
Practice 5­5
Nov 30­12:53 PM
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