A = 2a^4 +4a³b+10a²b² - 3a²b - 6ab² - 15b³
B = x^4 +x³y +x²y² + xy³ - x³y - x²y² - xy³ - y^4 = x^4 +x³y + xy³ - x³y - xy³ - y^4
C = 5a^5 +19a³b -25a²b² - 15ab³ -4a³b -8a²b² +20ab³ - 12b^4 =
= 5a^5 +15a³b -33a²b² +5ab³ - 12b^4
<span>sin²t·cos²t+sin⁴t / sin²t·cos²t+cos⁴t-1=sin</span>²t(cos²t+sin²t)/[cos²t(sin²t+cos²t)-1]=
=sin²t/(cos²t-1)=sin²t/(-sin²t)=-1
9n*(n-2)-(3n+1)²=9n²-18n-9n²-6n-1=-24n-1=-24*(-1⁵/₁₂)-1=
=-24*(-17/12)-1=-2*(-17)-1=34-1=33.
2) х18^(х9:х7)
х18^х2=х20
4) (х4^х3):(х3^х2)
х7:х5=х2