1) f(x)=2x^2+1/3x^3
f'(x) = 4x+x^2
y=f(x0)+f'(x0)*(x-x0)
f(x0) = 18-9=9
f'(x0) = -12+9 = -3
y=9-3(x+3) = -3x
2)f(x)=(x+1) / (x-1)
f'(x) = x-1 -(x+1) / (x-1)^2 = -2/(x-1)^2
y=f(x0)+f'(x0)*(x-x0)
f(x0)=3
f'(x0) = -2
y=3-2(x-2) = -2x+7
3) f(x)=1/3x^2-2x
f'(x) = 2x/3 - 2
y=f(x0)+f'(x0)*(x-x0)
f(x0)=3-6= -3
f'(x0) = 0
y= -3
4) f(x)=x^2+1/x
f'(x)=2x-1/x^2
y=f(x0)+f'(x0)*(x-x0)
f(x0)=4,5
f'(x0)=3/4
y=4,5+3/4(x-2) = 3x/4 - 3