1) 4+3=8x-2x
7=6x
x=7\6
2)3x-3=4x+8
-8-3=4x-3x
-11=1x
x=-11
(a+b)(a^2-ab+b^2)=a^3-a^2b+ab^2+ a^2b-ab^2+b^3=a^3+b^3
(x-1)(x^3+x^2+x+1)=x^4+x^3+x^2+x-x^3-x^2-x-1=x^4-1
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
Sin²α-tgα*ctgα=sin²α-1=-cos²α
Решение задания приложено