For the following linear system Ax=b, find the least square solutions. (a). A= ⎣
⎡
​
1
2
−1
​
2
4
−2
​
⎦
⎤
​
,b= ⎣
⎡
​
3
2
1
​
⎦
⎤
​
(b) A= ⎣
⎡
​
1
−1
1
​
1
3
2
​
3
1
4
​
⎦
⎤
​
,b= ⎣
⎡
​
−2
0
8
​
⎦
⎤
​