x2 - (m+1)x + m + 4 = 0
If the equation has ral roots, then the discriminant must be positive:
Let us verify:
d = b2 - 4ac > 0
==> (m+1)2 - 4*1* (m+4) > 0
==> m2 + 2m + 1 - 4m - 16 > 0
==> m2 -2m - 15 > 0
==> (m-5)(m+3) >0
==> m-5 > 0 and (m+3)>0 OR (m-5)< 0 and m+3 < 0
==> m > 5 and m > -3 OR m<5 and m<-3