The FOIL Method

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The FOIL Method

• A method used to help students remember how to
  multiply binomials.

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One way that binomials could be used is to find
area.

• Students learn at a young age how find the area
  of a surface
• Many students learn how to find area by using
  algebra tiles
• For example a piece of land that is
• 32 X 47 acres has an area of
• 1504 squared acres
• Continued on the next slide

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Area

• 30 2
• 40 1200 80
• 7 210 14
• So the area of this piece of land would be
• 120014210801504

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The same idea can be used to solve binomials

• One example would be (x2) (x5)
• x 2
• x
• 5
• Continued on the next slide

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Area

• (x2) (x5)
• x 2
• x x2 2x
• 5 5x 10
• So the area would be x2 2x 5x 10 x2 7x 10

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• One way to solve
• Binomials without
• using algebra tiles
• is to use the FOIL Method

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What does FOIL stand for?

• First (multiply the first term of each
  binomial together)
• Outer (multiply the two outside terms
  together)
• Inner (multiply the two inside terms
  together)
• Last (multiply the last term of each binomial
  together)

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The first step in FOIL

• (x-y) (xy)
• First multiply the first term of each binomial
  together
• x x x2

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The second step in FOIL

• (x-y) (xy)
• Outer multiply the two outside terms together
• x y xy

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The third step in FOIL

• (x-y) (xy)
• Inner multiply the two inside terms together
• -y x -yx

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The fourth step in FOIL

• (x-y) (xy)
• Last multiply the last term of each binomial
  together
• -y y -y2

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The last step

• Add all the term together in descending order of
  the power of the variable
• (x2) (-y2) (xy) (-xy)
• (x2)-(y2)

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Some pages to visit!!

• Algebra Help
• Algebra Expansion by FOIL Method
• The Math Lab