j)
(1-x)/(1+x)= (1+x-2x)/(1+x)= (1-2x/(1+x)
atunci
f(x) =((1-x)/(1+x))³= (1-2x/(x+1))³
tinem cont ca (f³(x)) '= 3 f²(x) * f '(x)
dexci
f'(x)= 3(1-2x/(x+1))² *(-2) *(x/(x+1))'
dar
(x/(x+1)' =(1-1/(x+1))'= 1/(x+1)²
atunci
f'(x)=3(1-2x/(x+1))² *(-2) *(x/(x+1))'= 3(1-2x/(x+1))² *(-2) *1/(x+1)²
deci
f'(1)=3*(1-2/4) * (-2)*1/4=3*(1/2) *(-1/2)=-3/4