what we're going to do in chapter 5 5/l5.2/slides.pdf · l5.2 1) determine if opens up or down 2)...
TRANSCRIPT
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What we're going to do in chapter 5 L5.2Quadratic equations:
• Degree 2 equations• Example: y = 2x2 + 3x 6
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Quadratic equation basics L5.2Quadratic equations:
• "Standard" form: y = ax2 + bx + c, a ≠ 0
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Identify a, b, & c for the following quadratics L5.2
1) y = 4x2 3x + 1
2) y = x2 + x 2
3) y = 3x2 x + 4
4) y = 1/3x2 3x 7
5) y = x2 2x + 6
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Write the equation in standard form L5.2
1) 3x + 1= 4x2 + 2
2) 2x2 2x= x2 x 2
3) 3x2 4 = x
4) 1/2x2 + 11/5x +3 = 5/6x2 4/5x 10
ax2 + bx + c = 0
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Quadratic equation basics L5.2• Standard form: y = ax2 + bx + c , a ≠ 0• Ushaped graph
• Can open up or down⇒ a positive opens up⇒ a negative opens down
⇒ called a parabola
a positive
a negative
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Indicate if the parabola opens up or down L5.2
1) y = 4x2 3x + 1
2) y = x2 + x 2
3) y = 3x2 x + 4
4) y = 1/3x2 3x 7
5) y = x2 2x + 6
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⇒ a positive opens up⇒ a negative opens down
do #5 9 oddpg 239
5) down
7) down
9) up
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Quadratic equation basics L5.2• Standard form: y = ax2 + bx + c , a ≠ 0• Ushaped graph
• Can open up or down
• Has a vertex
⇒ a positive opens up⇒ a negative opens down
⇒ x coord is at x = b2a⇒ plug that back in to find y coord
⇒ called a parabola
Vertex
Vertex
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Identify the vertex of the parabola L5.2
1) y = 3x2 + 6x 2
2) y = x2 2x 3
3) y = 7x2 + 2x 10
• Vertex⇒ x coord is at x = b2a⇒ plug that back in to find y coord
do #11 15 oddpg 239
11) (5/4, 55/8)
13) (1/4, 3/4)
15) (1, 25)
find vertex only
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Quadratic equation basics L5.2• Standard form: y = ax2 + bx + c , a ≠ 0• Ushaped graph
• Can open up or down
⇒ called the Axis of symmetry
• Has a vertex
• Symmetric around a vertical line
⇒ a positive opens up⇒ a negative opens down
thru the vertex
⇒ x coord is at x = b2a⇒ plug that back in to find y coord
⇒ Axis of symmetry is the line x = b2a
⇒ called a parabola
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Identify the axis of symmetry of the parabola L5.2
1) y = 3x2 + 6x 2
2) y = x2 2x 3
3) y = 7x2 + 2x 10
⇒ Axis of symmetry is the line x = b2a
do #11 15 oddpg 239
11) (5/4, 55/8)
13) (1/4, 3/4)
15) (1, 25)
find axis of symmetry
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How to sketch a parabola L5.21) Determine if opens up or down
2) Find the vertex
3) Tchart 2 points on each side of vertex
4) Plot the points & connect them
5) Make sure it opens in the right direction
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Sketch y = x2 + 8x + 16 L5.21) Determine if opens up or down
2) Find the vertex
3) Tchart 2 points on each side of vertex
4) Plot the points & connect them
5) Make sure it opens in the right directiondo #29 39 odd
pg 240
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L5.2 HomeworkPg 239 #14, 519 odd, 2328, 2939 odd, 4760
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