   We already know how to factor these
    types of quadratic expressions:
    ◦ General Trinomial:
      2x2 – 5x – 12 = (2x + 3)(x – 4)
    ◦ Perfect Square Trinomial:
      x2 + 10x + 25 = (x + 5)2
    ◦ Difference of Two Squares:
      4x2 – 9 = (2x + 3)(2x – 3)
    ◦ Common Monomial Factor:
      6x2 + 15x = 3x(2x + 5)
 Sum of Two Cubes:
  a3 + b3 = (a + b)(a2 – ab + b2)
 Example:
  x3 + 8 = (x + 2)(x2 – 2x + 4)

 Difference of Two Cubes:
  a3 – b3 = (a – b)(a2 + ab + b2)
 Example:
  8x3 – 1 = (2x – 1)(4x2 + 2x + 1)
 Factor each polynomial.
 x3 + 27




   8x3 - 125
   Factor x3 + 343
 You can sometimes factor out a
  monomial, then use sum/difference of
  cubes.
 (When powers are 3 apart.)
 Example:
  ◦ 64x4 – 27x
   Factor 3x4 – 24x
 Sometimes we can factor by grouping
  pairs of terms with a common monomial
  factor:
  ra + rb + sa + sb = r(a + b) + s(a + b)
                    = (r + s)(a + b)
 Example:
  x3 – 2x2 – 9x + 18
   Factor the polynomial.
    x2y2 – 3x2 – 4y2 + 12
   Factor x3 – 2x2 +4x - 8
 An expression of the form
  au2 + bu + c where u is any expression
  in x is in quadratic form.
 We can factor these like a quadratic.
 Example:
  Factor 81x4 - 16
   Factor 4x6 – 20x4 + 24x2




   Factor x4 + 4x2 - 21
   Factor x4 + 3x2 + 2
 Remember the zero product property?
 If AB = 0 then A = 0 or B = 0


 To solve, factor and set each factor equal
  to zero. Then solve for x.
 Only include real solutions.
 May have up to n solutions. (where n is
  the degree.)
 Find the real number solutions of the
  equation.
 2x5 + 24x = 14x3




   2x5 – 18x = 0
   A large concrete block is discovered by
    archaeologists with a volume of 330 cubic
    yards. The dimensions are x yards high
    by 13x – 11 yards long by 13x – 5 yards
    wide. What is the height?
   You are building a bin to hold mulch for
    your garden. The bin will hold 162 cubic
    feet of mulch. The dimensions are x ft
    by 5x – 6 ft by 5x – 9 ft. How tall will the
    bin be?

6.4 factoring and solving polynomial equations

  • 2.
    We already know how to factor these types of quadratic expressions: ◦ General Trinomial: 2x2 – 5x – 12 = (2x + 3)(x – 4) ◦ Perfect Square Trinomial: x2 + 10x + 25 = (x + 5)2 ◦ Difference of Two Squares: 4x2 – 9 = (2x + 3)(2x – 3) ◦ Common Monomial Factor: 6x2 + 15x = 3x(2x + 5)
  • 3.
     Sum ofTwo Cubes: a3 + b3 = (a + b)(a2 – ab + b2)  Example: x3 + 8 = (x + 2)(x2 – 2x + 4)  Difference of Two Cubes: a3 – b3 = (a – b)(a2 + ab + b2)  Example: 8x3 – 1 = (2x – 1)(4x2 + 2x + 1)
  • 4.
     Factor eachpolynomial.  x3 + 27  8x3 - 125
  • 5.
    Factor x3 + 343
  • 6.
     You cansometimes factor out a monomial, then use sum/difference of cubes.  (When powers are 3 apart.)  Example: ◦ 64x4 – 27x
  • 7.
    Factor 3x4 – 24x
  • 8.
     Sometimes wecan factor by grouping pairs of terms with a common monomial factor: ra + rb + sa + sb = r(a + b) + s(a + b) = (r + s)(a + b)  Example: x3 – 2x2 – 9x + 18
  • 9.
    Factor the polynomial. x2y2 – 3x2 – 4y2 + 12
  • 10.
    Factor x3 – 2x2 +4x - 8
  • 11.
     An expressionof the form au2 + bu + c where u is any expression in x is in quadratic form.  We can factor these like a quadratic.  Example: Factor 81x4 - 16
  • 12.
    Factor 4x6 – 20x4 + 24x2  Factor x4 + 4x2 - 21
  • 13.
    Factor x4 + 3x2 + 2
  • 14.
     Remember thezero product property?  If AB = 0 then A = 0 or B = 0  To solve, factor and set each factor equal to zero. Then solve for x.  Only include real solutions.  May have up to n solutions. (where n is the degree.)
  • 15.
     Find thereal number solutions of the equation.  2x5 + 24x = 14x3  2x5 – 18x = 0
  • 16.
    A large concrete block is discovered by archaeologists with a volume of 330 cubic yards. The dimensions are x yards high by 13x – 11 yards long by 13x – 5 yards wide. What is the height?
  • 17.
    You are building a bin to hold mulch for your garden. The bin will hold 162 cubic feet of mulch. The dimensions are x ft by 5x – 6 ft by 5x – 9 ft. How tall will the bin be?