Solution (source code)

= Solution

From zero, the first update is \b[$x_1=(-1,3/2,1/4)^T$]. For the next update, the first component is $-1+3/2-1/4=1/4$, the second is $3/2-(1/2)(3/2)=3/4$, and the third is $1/4-(3/4)(3/2)+(1/2)(1/4)=-3/4$. Therefore \b[$x_2=(1/4,3/4,-3/4)^T$].