5х(4x) - 5х(x(3x) - 2) = 020x - 5x(3x^2 - 2) = 020x - 15x^3 + 10x = 030x - 15x^3 = 015x(2 - x^2) = 0x = 0, +/-√2
5х(4x) - 5х(x(3x) - 2) = 0
20x - 5x(3x^2 - 2) = 0
20x - 15x^3 + 10x = 0
30x - 15x^3 = 0
15x(2 - x^2) = 0
x = 0, +/-√2