Section 1.5

 

21.

         

 

27.             4x – 5[3 – (x – 4)] = 4x – 5[3 – x + 4] = 4x – 5[7 – x] = 4x – 35 + 5x = 9x – 35

 

31.              when x = 12

 

 

33.      x³ – x² + x – 1 when x is –2

(-2)³ – (-2)² + (-2) – 1 = -8 – 4 – 2 – 1 = -15

 

 

39.             (3a + 5)(2a³ – 3a² + a)

 

 2a³ –   3a² +   a

   X                 3a +   5

         10a³ – 15a² + 5a

  6a⁴ – 9a³ +  3a²         

  6a⁴ +  a³ – 12a² + 5a     

 

 

51.

         

 

67.             (x – 2)³ = (x – 2)(x – 2)(x – 2) = (x² – 2x – 2x + 4)(x – 2)

  = (x² – 4x + 4)(x – 2)

  = x³ – 2x² –4x² + 8x + 4x – 8

  = x³ – 6x² + 12x – 8

 

 71.     (b² + 8)(a2 +1) = a²b² + b² + 8a² + 8 = a²b² + 8a² + b² + 8

75.             (x + 1)² + (x + 2)² + (x + 3)²

= x² + 2x + 1 + x² + 4x + 4 + x² + 6x + 9

= 3x² + 12x + 14