Ответ:
- \(x^2y+yxy=x^2y+xy^2\).
- \(3x\cdot6y^2-5x^2\cdot7y=18xy^2-35x^2y\).
- \(2a\cdot a^2\cdot3b+a\cdot8c=6a^3b+8ac\).
- \(8x\cdot3y\cdot(-5y)-7x^2\cdot(-4y)=-120xy^2+28x^2y\).
- \(11a^5-8a^5+3a^5+a^5=(11-8+3+1)a^5=7a^5\).
- \(1.9x^3-2.9x^3-x^3=(1.9-2.9-1)x^3=-2x^3\).
- \(20xy+5yx-17xy=(20+5-17)xy=8xy\).
- \(8ab^2-3ab^2+ab^2-7ab^2=(8-3+1-7)ab^2=-ab^2\).
Ответ: 1) \(x^2y+xy^2\); 2) \(18xy^2-35x^2y\); 3) \(6a^3b+8ac\); 4) \(-120xy^2+28x^2y\); 5) \(7a^5\); 6) \(-2x^3\); 7) \(8xy\); 8) \(-ab^2\).
