(a+b)a-b(a+b)=(a^2+ab)-(ab+b^2)=a^2+ab-ab-b^2=a^2-b^2=(a-b)(a+b)
a(b+3)-b(3+b)=(ab+3a)-(3b+b^2)=ab+3a-3b-b^2
1) a+b²-3a= -2a+b²
2) x+2x+3y-3x=0+3y= 3y
3) -2x+6y+5x•4-y²= -2x+6y+20x-y²= 18x+6y-y²
4) h²g²+h•5gh•7g= (1+5•7)h•hg•g= (1+35)h•hg•g= 36h•hg•g= 36g²h²
5) (nmk)³-n³m•m²k³= (kmn)³-k³m³n³= k³m³n³-k³m³n³
6) -7s²d⁴r³+9•(-d²r•s)²•r= -7s²d⁴r³+9•(d²rs)²•r= -7s²d⁴r³+9d⁴r²s²r= (-7+9)s²d⁴r²r= 2s²d⁴r²r= 2d⁴r³s²
7) 3f³•f-f²•(-f²)= 3f³f+f²•f²= (3+1)f²f•f= 4f²f•f= 4f⁴.
1.
7,5a-(2,3a+0,4a³)= 7,5a-2,3a+0,4a³= 0,4a³+5,2a
(4,2x-x²+6)+0,4x²-(9,3x+1,4x²=
=4,2x-x²+6+0,4x²-9,3x-1,4x²=-2x²-5,1x+6
(6b³-2b²+1)*(-2b)=-12b^4+4b³-2b
5a(2a²-8a+4)=10a³-40a²+20a
2.
a) 2x-7(4-x)=17
2x-28+7x=17
9x=17+28
9x=45
X=9