[tex]\displaystyle 5a).2x^2+5x^2-7x^2+6x^2=7x^2-7x^2+6x^2=6x^2 \\ b).-3a^2+a^2+(5a^2-a^2)+6a^2=-3a^2+a^2+4a^2+6a^2= \\ =-2a^2+4a^2+6a^2=2a^2+6a^2=8a^2 \\ c).12a^3-9a^3+5a^3+(16a^3-14a^3)=12a^3-9a^3+5a^3+2a^3= \\ =3a^3+5a^3+2a^3=8a^3+2a^3=10a^3 \\ d).(5x^2-3x^2+9x^2)-(21x^2-15x^2)=(2x^2+9x^2)-6x^2= \\ =11x^2-6x^2=5x^2[/tex]
[tex]\displaystyle 6a).0,4x^2-0,3x^2+(2,7x^2-1,5x^2+x^2)-(4,9x^2-2,7x^2)= \\ =0,4x^2-0,3x^2+(1,2x^2+x^2)-2,2x^2=\\=0,4x^2-0,3x^2+2,2x^2-2,2x^2=0,1x^2+2,2x^2-2,2x^2=0,1x^2 \\ b).-10,5a^2+(a^2-0,1a^2-0,9a^2)+2,35a^2+1,65a^2= \\ =-10,5a^2+(0,9a^2-0,9a^2)+2,35a^2+1,65a^2= \\ =-10,5a^2+0+2,35a^2+1,65a^2=-10,5a^2+2,35a^2+1,65a^2= \\ =-8,15a^2+1,65a^2=-6,5a^2 [/tex]
[tex]\displaystyle c).(2,25y^3+3,5y^3-0,75y^3)+(13,7y^3+2,3y^3-15y^3)= \\ =(5,75y^3-0,75y^3)+(16y^3-15y^3)=5y^3+y^3=6y^3 \\ d).(3,3a^2b^2+1,7a^2b^2)-(5,9a^2b^2-2,6a^2b^2-4,2a^2b^2)+0,1a^2b^2= \\ =5a^2b^2-(3,3a^2b^2-4,2a^2b^2)+0,1a^2b^2= \\5a^2b^2-(-0,9a^2b^2)+0,1a^2b^2=5a^2b^2+0,9a^2b^2+0,1a^2b^2= \\ =5,9a^2b^2+0,1a^2b^2=6a^2b^2[/tex]
[tex]\displaystyle 7a).2a^2b+3ab^2-5a^2b+6ab^2+9a^2b-4ab^2=6a^2b+5ab^2 \\ b).(2x^2+4xy)+(y^2-2xy)-(x^2+4y^2-5xy)+(x^2-y^2)= \\ =2x^2+4xy+y^2-2xy-x^2-4y^2+5xy+x^2-y^2= \\ =2x^2+7xy-4y^2 \\ c).11m+(3n-5m+6)-(4m-2n-8)= \\ =11m+3n-5m+6-4m+2n+8=2m+5n+14 \\ d).(12m^2-5m+n^2)-(2n^2+6m-3m^2)-(12m^2-mn)= \\ =12m^2-5m+n^2-2n^2-6m+3m^2-12m^2+mn= \\ =3m^2+mn-11m-n^2[/tex]
[tex]\displaystyle 8a).12a-9a+\underline{12a}=15a \\ b).3x+5x-\underline{4x}=4x \\ c).2x^2-4x^2+\underline{(-x^2)}+3x^2=0 \\ d).11ab-\underline {8ab}-ab=2ab \\ e).\underline{a}+12a-11a=2a \\ f).3abc-\underline{abc}-abc=abc \\ 9a).(3x+10y)-(5x+4y)-(7x-2y)= \\ =3x+10y-5x-4y-7x+2y=-9x+8y \\ b).(4a^2-5ab)-(ab+3b^2)-(a^2-b^2)= \\ =4a^2-5ab-ab-3b^2-a^2+b^2=3a^2-6ab-2b^2[/tex]
