Let At=13225t47−t−6 then the value(s) of t for which inverse of At does not exist.
– 2, 1
3, 2
2, – 3
3, – 1
since At-1 does not exist, At =0
⇒(−30−t(7−t))−3(−12−4t)+2(14−2t−20)=0
⇒t2+t−6=0⇒t=−3,2