7.3 Factoring TrinomialsObjective:  To factor trinomials of the form   x2 + bx + cFrameworks:   10.P.5
FOIL With a Negative and a Positive(x - 3)(x + 5)First terms:   x and x         x2Outside terms:  x and 5            +5xInside terms:  3 and x               -3xLast terms:  3 and 5                          15Answer:                             x2 + 2x  - 15
FOIL With a Negative and a Positive(x + 3)(x - 5)First terms:   x and x         x2Outside terms:  x and 5            -5xInside terms:  3 and x               +3xLast terms:  3 and 5                          15Answer:                             x2 - 2x  - 15
FactoringThe product of 2 binomials is usually a trinomial:          (x + 3)(x – 2) = x2 + x - 6To factor a trinomial means to express it as a product of two binomials.To factor                  x2 + x – 6    is to rewrite it as  (x + 3)(x – 2)
Signs Flowchart
FactoringTo solve this, we use FOIL in reverse:   x2 + x – 6   =  (x      )(x        )Now look at the signs: x2 + x – 6   =  (x +    )(x -      )Then guess & check to find the last 2 numbers, remembering that the two terms multiplied are -6 and added are + 1x2 + x – 6   =  (x +    )(x -      )
FactoringSolve:   x2 - 2x – 48   =  (x      )(x        )Now look at the signs: x2 -2x – 48   =  (x +    )(x -      )Guess & check: x2 -2x – 48   =  (x +    )(x -      )
Factor x2 - 13x + 40
Factor x2 + 11x + 24
Factor x2 - 15x + 56
Factor x2 - x - 20
Factor x2 - 2x - 24
Do p. 254 1-12

Algebra 7 Point 3

  • 1.
    7.3 Factoring TrinomialsObjective: To factor trinomials of the form x2 + bx + cFrameworks: 10.P.5
  • 3.
    FOIL With aNegative and a Positive(x - 3)(x + 5)First terms: x and x x2Outside terms: x and 5 +5xInside terms: 3 and x -3xLast terms: 3 and 5 15Answer: x2 + 2x - 15
  • 4.
    FOIL With aNegative and a Positive(x + 3)(x - 5)First terms: x and x x2Outside terms: x and 5 -5xInside terms: 3 and x +3xLast terms: 3 and 5 15Answer: x2 - 2x - 15
  • 5.
    FactoringThe product of2 binomials is usually a trinomial: (x + 3)(x – 2) = x2 + x - 6To factor a trinomial means to express it as a product of two binomials.To factor x2 + x – 6 is to rewrite it as (x + 3)(x – 2)
  • 6.
  • 7.
    FactoringTo solve this,we use FOIL in reverse: x2 + x – 6 = (x )(x )Now look at the signs: x2 + x – 6 = (x + )(x - )Then guess & check to find the last 2 numbers, remembering that the two terms multiplied are -6 and added are + 1x2 + x – 6 = (x + )(x - )
  • 8.
    FactoringSolve: x2 - 2x – 48 = (x )(x )Now look at the signs: x2 -2x – 48 = (x + )(x - )Guess & check: x2 -2x – 48 = (x + )(x - )
  • 9.
    Factor x2 -13x + 40
  • 10.
    Factor x2 +11x + 24
  • 11.
    Factor x2 -15x + 56
  • 12.
  • 13.
  • 14.