Probability

If the probability that the random variable \(\mathrm{X}\) takes values \(x\) is given by \(\mathrm{P}(\mathrm{X}=x)=\mathrm{k}(x+1) 3^{-x}, x=0,1,2,3, \ldots\), where \(\mathrm{k}\) is a constant, then \(\mathrm{P}(\mathrm{X} \geq 2)\) is equal to :