Solution - Simplification or other simple results

Step  1  :

 1.1     42 = 2•3•7

(42)² = (2•3•7)² = 2² • 3² • 7²

Equation at the end of step  1  :

  (43 • (22•32•72)) -  6

Step  2  :

Equation at the end of step  2  :

  (43•22•32•72) -  6

Step  3  :

Final result :

  43 - 6