(3-sina)*(3+sina)+(2-cosa)*(2+cosa)=3² -(sinα)² +2² -(cosα)² = 9 +4 -(sin²α+cos²α) =13 -1=12.
(x^(-1) y^(-2))^(-2)=(1/xy²)^(-2)=(xy²)²=x² y^4
(1/2 a^(-3) b³)^(-2)=(b³ /2a³)^(-2)=4a^6/( b^6)
(0.25m^(-2) n²)^(-3)=(n²/4m²)^(-3)=(4m²/n²)³=64m^6 / n^6
(a³b^(-1))²=a^6 /b³
(-3p³q^(-1))²=9p^6/q²
(1/3x^(-3) y²)³=y^6 / 27x^9