6+12х=6+10х
12х-10х=6-6
2х=0
х=0
1. a) 5a^2-10ab+5b^2
b) 2m^2-6m^2+6m=6m-4m^2
в) -3x^2-3xy-3y^2
г) 4n^2+8n^4-12n^5
д) 2b^3-2ab^3+8a^2b^2
e) -12c^3d-9c^4d+3c^5
2. a) 3n^6+6n^5-12n^4
b) -6m^4+4m^5-2m^6
v) 10x^2y^2-5x^3y^3-5x^4y^2
cos(30°+a)-cos(30°-a) = cos30cosa-sin30sina - (cos30cosa+sin30sina)