Given, x2+mx+n=0 has real roots. ∴ m2−4n≥00≤m,n≤10,m2≥4n m=10,n={0,1,2,...,10}=11 m=9,n={0,1,2,...,10}=11 m=8,n={0,1,2,...,10}=11 m=7,n={0,1,2,...,10}=11 m=6,n={0,1,2,...,9}=10 m=5,n={0,1,2,...,6}=7 m=4,n={0,1,2,3,4}=5 m=3,n={0,1,2}=3 m=2,n={0,1}=2 m=1,n={0}=1 m=0,n={0}=1 ∴ Number of order pair of (m,n) is