(P+Q′+R′).(P+Q′+R).(P+Q+R′) is in pos format moreover every term is a maxterm
In Maxterm 0 represent variable is in true form and 1 represent variable is in complemented form.
therefore (P+Q′+R′) = (011)2 = 3
(P+Q′+R) = (010)2 = 2
(P+Q+R′) = (001)2 = 1
(P+Q′+R′).(P+Q′+R).(P+Q+R′) ===> ΠM(1,2,3) ===> in K-Map 1,2,3 cells are should be 0 and there are no don't care terms that means remaining all are filled by 1.
if you want simplified expression in pos format then cover all zeros
if you want simplified expression in sop format then cover all ones
therefore required expression is P+Q'R'