m+1+m^2/4
=(m/2)²+2×m/2×1+1²
=(m/2+1)²
n^2/9-2/3n+1
=(n/3)²-2×n/3×1+1²
=(n/3-1)²
-x^3-2x^2-x
=-x(x²+2x+1)
=-x(x+1)²