The density of a metal bar 3 metres long is is given by ρ ( x ) = 1 x + 1 {\displaystyle \rho (x)={\frac {1}{\sqrt {x+1}}}} kilograms per metre ( 0 ≤ x ≤ 3 {\displaystyle 0\leq x\leq 3} ).
Find the mass of the bar.
