A) f`(x)=2-3/√x^3
f`(9)=2-3/√9^3=2-3/27=2-1/9=17/9
b) f`(x)=((2x-4)`(x^2+1)-(2x-4)(x^2+1)`/(x^2+1)^2=(2(x^2+1)-2x(2x-4)/(x^2+1)=(2x^2+2-4x^2+8x)/(x^2+1)=(-2x^2+8x+2)/(x^2+1)
f`(3)=(-2*3^2+8*3+2)/(3^2+1)=(-18+24+2)/10=0,8
в) f`(x)=(2x-4)^5`*(2x-4)`=10(2x-4)^4
f`(6)=10(2*6-4)^4=10*8^4=10*4096=40960