\ begin {ecuation*}\ begin {aligned} a\ left [\ begin {array} {r} {r} 2\\ 1\ end {array}\ right] + b\ left [\ begin {array} {r} 1\\ 2\ end {array}\ right] & =\ left [\ begin {array} {r} -1\\ 4\ end {a...\ begin {ecuation*}\ begin {aligned} a\ left [\ begin {array} {r} {r} 2\\ 1\ end {array}\ right] + b\ left [\ begin {array} {r} 1\\ 2\ end {array}\ right] & =\ left [\ begin {array} {r} -1\\ 4\ end {array}\ derecha]\\\ izquierda [\ begin {array} {r} 2a\\ a\ end {array}\ right] +\ left [\ begin {array} {r} b\\ 2b\ end {array}\ right] & =\ left [\ begin {array} {r} -1\\ 4\ end {array}\ derecha]\\\\ izquierda [\ begin {array} {r} 2a+b\\ a+2b\ end {array}\ right] & =\ left [\ begin {array} {r} -1\\…
