4x^4-5x^2+1=0 Замена: x^2 = t; t >= 0 4t^2-5x^t+1=0 D = 25-16=9; t1 = (5+3)/8 = 1 t2 = (5-3)/8 = 1/4 x^2=1 x^2=1/4 x=+-1 x=+-1/2 Ответ: +-1, +-1/2