Х+1=y =>x=y-1; x-2y=7 =>x=7-2y
1. (y+2)(y+3)-(y^2+y) = y^2 + 3y + 2y + 6 - y^2 - y = 4y + 6
2. <span>(c+2)c+(c+3)(c-3) = c^2 + 2c + c^2 - 9 = 2c^2 + 2c - 9
3. </span><span>(6a^2 – 3a + 8) – (2a^2 – 5) = 6a^2 - 3a + 8 - 2a^2 + 5 = 4a^2 - 3a + 13
4. </span><span>(7х^2 – 5х + 3) – (5х^2 – 4) = 7x^2 - 5x + 3 - 5x^2 + 4 = 2x^2 - 5x + 7
5. </span><span>(4b^2 – 2b + 3) – (6b – 7) = 4b^2 - 2b +3 - 6b + 7 = 4b^2 - 8b + 10</span>
(x-7)-(2x+9)=-13
Раскроем скобки: x-7-2x-9=-13
Упрощаем и переносим -16 в правую часть уравнения, получаем:
-x-16=-13
-x=3
x=-3