1.(m+n)^3+(m-n)^3-2m=(m+n+m-n)(m²+2mn+n²-m²+n²+<span>m²-2mn+n²)-2m=2m(m²+2n²-1)
2. </span>(a-b)^3-(c+d)^3-a+b+c+d=(a-b-c-d)(a²-2ab+b²+ac+ad-bc-bd+c²+2cd+d²)-(a-b-c-d)=(a-b-c-d)(a²-2ab+b²+ac+ad-bc-bd+<span>c²+2cd+d²-1)</span>
3ху*(4уz) = 12xy²z
(3b⁴c)²=9b⁸c²
(x+2)(x+5)=x²+5x+2x+10=x²+7x+10
(5a² -8ab +2a) :2 = 2,5а²-4ab+a
3y²+5y+7 -2y²-3y -5 = (3y² -2y²) + (5y-3y) + (7-5) = y² +2y +2
6,5-2х=3х-3,7
-2х-3х=-3,7-6,5
-5х=-10,2
х=-10,2:(-5)
х=2,04
проверка 6,5-2*2,04=3*2,04-3,7
6,5-4,08=6,12-3,7
2,42=2,42 решение верно