1) 2x-1/x+7=3x+4/x-1
(x+7)(3x+4)=(2x-1)(x-1)
3x²+4x+21x+28=2x²-2x-x+1
3x²-2x²+4x+21x+2x+x+28-1=0
x²+28x+27=0
Д=784-4*1*27=784-108=676(26)
x1=-28+26/2=-1
x2=-28-26/2=-27
2) x^5+x^3/x^(-1)+x^(-3) = x^5+x^3 / 1/x + 1/x^3 = x^5+x^3 / x^3+x / x^3 = x^5+x^3 * x^3 / x^3+x = x^3 (x^2+1) * x^3 / x(x^2+1) = x^3*x^2 = x^5