Tìm X biết: x x 2 + x x 3 + x x 4 + x = 2130

x x 2 + x x 3 +  x x 4 +  x = 2130

x x 2 + x x 3 +  x x 4 +  x x 1= 2130

x x (2 + 3 + 4 + 1) = 2130

x x 10 = 2130

x      = 2130 : 10

x      = 213