1) cbf
2) ln(x)*(x^2+1)^-1, product rule:
derivative: 1/(x^3+x) - 2x*ln(x)/(x^2+1) = (1+2x^2*ln(x))/(x^3+x)
3) y'=1/x, y'(e)=1/e
tangent: y=x/e+b, 1=e/e+b so b=0
tangent: y=x/e
4) Pardon wtf bbq?
Int dx/(2x+9) from 36 to a = ln(k)
Int dx/(2x+9) = ln(2x+9)/2
For terminal 36, the answer is...