(149 - х*х*х) * 7 = 168
149 - х*х*х = 168 : 7
149 - х*х*х = 24
х*х*х = 149 - 24
х*х*х = 125
Перебираем, начиная с 1:
x = 1 x*x*x = 1*1*1 = 1
x = 2 x*x*x = 2*2*2 = 8
x = 3 x*x*x = 3*3*3 = 27
x = 4 x*x*x = 4*4*4 = 64
x = 5 x*x*x = 5*5*5 = 125
Ответ: х = 5