Question

1 -2 4 x
3 4 7 y
1 4 6 z

What I will do elemeantry row operations to turn diagonal matrix

Answer 1

wow these are not fun to do by typing...
well you can multiply a scalar by any row, you can add rows
the goal is to have 1's in diagonal and zeros elsewhere

you should first try to work on 1st column, get bottom 2 numbers to be 0
then 2nd column, get bottom number to be 0
then work on eliminating top corner numbers

Answer 2

im assuming x,y,z represent constants

Answer 3

You know how to set a matrix to echelon form? And then to row reduced echelon form?