помогите решить домашнее задание по линейной алгебре Пожалуйста

1. Find the distance between the parallel lines [x, y]=[0,1]+ s[-1,1] and [x,y]=[0,-1]- t[2,-2]
2. Find a system of two linear equation in x and y whose solution set is given by the parametric equitations x=t, y=5t-2
3. What is wrong with following proof that every matrix with at least two rows is row equivalent to a matrix with a zero row?
Proof:
Perform R2+R1 and R1+R2
Now rows 1 and 2 are identical.
Now perform R2-R1 to obtain a row of zeros in the second row.