3а
=(x-4b)(x²+4xb+16b²)+64b³+x³+b²=x³-64b³+x³+b²=2x³+b²
x=1,b=-2 2*1+4=2+4=6
3б
=(c³-1)(c^6+c³+1)/5(c²+c+1):4(c^6+c³+1)/10(c+1) - 3=
=(c-1)(c²+c+1)(c^6+c³+1)/5(c²+c+1) *10(c+1)/4(c^6+c³+1) -3=(c²-1)/2 -3
c=-3 (9-1)/2 -3=4-3=1
4
1)(a-b)/a(a+b)-a/b(a+b)=(ab-a²-b²)/ab(a+b)=-(a²-ab+b²)/ab(a+b)
2)1/(a+b)+b²/[a(a-b)(a+b)]=(a²-ab+b²)/[a(a-b)(a+b)]
3)-(a²-ab+b²)/ab(a+b) : (a²-ab+b²)/[a(a-b)(a+b)]=
=-(a²-ab+b²)/ab(a+b) * [a(a-b)(a+b)]/(a²-ab+b²)=-(a-b)/b=(b-a)/b