Solve 2(x+3)^3-(x-1)(x+1) show all steps

(x + 3)^3 = (x + 3)(x + 3)(x + 3)

(x + 3)(x + 3) = x(x + 3) + 3(x + 3) = x*x + 3*x + 3*x + 3*3 = x² + 3x + 3x + 9

= x² + 6x + 9

(x + 3)^3 = (x + 3)(x + 3)(x + 3) = (x² + 6x + 9)(x + 3)

(x² + 6x + 9)(x + 3) = x*(x² + 6x + 9) +3*(x² + 6x + 9)
     
                               = x³ + 6x² + 9x + 3x² + 18x + 27
 
                               = x³ + 6x² +3x² + 9x + 18x + 27
 
  (x + 3)^3               = x³ + 9x² + 27x + 27 

(x - 1)(x + 1) = x(x + 1) - 1(x + 1) = x*x + x*1 -1*x -1*1 = x² + x - x - 1 = x² - 1

2(x+3)^3-(x-1)(x+1) = 2*(x³ + 9x² + 27x + 27 ) - (x² - 1)
  
                                = 2x³ + 18x² + 54x + 54 - x² + 1
                                  
                                = 2x³ + 18x² - x² + 54x + 54
    
                                = 2x³ + 17x² + 54x + 54 

Hope this explains it.

The answer is 225 miles per 4.5 hours. hope this ; )