решите уравнения 
1)x^4-5x^2+4=0
2)9x^2-37x=0
3)2 1/5x+4,2=1 1/3(2-x)
4)1/x^2+1/x+6/x=-4 (1+x^2)/x^2
Заранее спасибо !

X^4 - 5X^2 + 4 = 0 X^2 = A ; A > 0 A^2 - 5A + 4 = 0 D = 25 - 16 = 9 ; √ D = 3 A1 = ( 5 + 3 ) : 2 = 4 A2 = 2 : 2 = 1X1 = + 2 X2 = - 2 X3 = + 1 X4 = - 1 -----------------------------9X^2 - 37X = 0 9X * ( X - 37 ) = 0 9X = 0 ; X = 0 X - 37 = 0 ; X = 37 ---------------------------------2 1/5 X + 4,2 = 1 1/3 * ( 2 - X ) 2,2X + 4,2 = 4/3 * 2 - 4/3X 2,2X + 4,2 = 8/3 - 4/3X 2,2X + 4/3X = 8/3 - 4,2 22/10X + 4/3X = 8/3 - 21/5 22X * 3 + 4X * 10 = 8 * 10 - 21 * 6 66X + 40X = 80 - 126 106X = - 46 X = - 46/106 = - 23/53 -------------------------------------( 1/ X^2 ) + ( 1/ X) + ( 6/ X ) = ( - 4 * ( 1+ X^2 ) / X^2 )X^2 ≠ 0 ; X ≠ 0 ( 1 + X + 6X ) / X^2 = ( - 4 - 4X^2 ) / X^2 1 + 7X = - 4 - 4X^2 4X^2 + 7X + 5 = 0 D = 49 - 80 = - 31 D < 0  Решений нет