а) (5x^3-3x^2-7)+(4+3x^2-5x^3) =5x^3 - 3x^2 - 7 + 4 + 3x^2 - 5x^3 =(5x^3 - 5x^3) + (-3x^2 + 3x^2) + (4 - 7) = 0 + 0 - 3 = -3.
б) (z^2-3z+2)+(4z+8)+(3z^2-5) =z^2 - 3z + 2 + 4z + 8 + 3z^2 - 5 =(z^2 + 3z^2) + (-3z + 4z) + (2 + 8 - 5) = 4z^2 + z + 5.
в) (3t^3-4t^2+7t)+(2t^2-6t+7) =3t^3 - 4t^2 + 7t + 2t^2 - 6t + 7 =(3t^3) + (-4t^2 + 2t^2) + (7t - 6t) + 7 = 3t^3 - 2t^2 + t + 7.
г) (2a^2+5a)+(-a^2+a)+(a^2-3a-5) =2a^2 + 5a - a^2 + a + a^2 - 3a - 5 =(2a^2 - a^2 + a^2) + (5a + a - 3a) + (5) = 2a^2 + 3a + 5.
а) (5x^3-3x^2-7)+(4+3x^2-5x^3) =
5x^3 - 3x^2 - 7 + 4 + 3x^2 - 5x^3 =
(5x^3 - 5x^3) + (-3x^2 + 3x^2) + (4 - 7) = 0 + 0 - 3 = -3.
б) (z^2-3z+2)+(4z+8)+(3z^2-5) =
z^2 - 3z + 2 + 4z + 8 + 3z^2 - 5 =
(z^2 + 3z^2) + (-3z + 4z) + (2 + 8 - 5) = 4z^2 + z + 5.
в) (3t^3-4t^2+7t)+(2t^2-6t+7) =
3t^3 - 4t^2 + 7t + 2t^2 - 6t + 7 =
(3t^3) + (-4t^2 + 2t^2) + (7t - 6t) + 7 = 3t^3 - 2t^2 + t + 7.
г) (2a^2+5a)+(-a^2+a)+(a^2-3a-5) =
2a^2 + 5a - a^2 + a + a^2 - 3a - 5 =
(2a^2 - a^2 + a^2) + (5a + a - 3a) + (5) = 2a^2 + 3a + 5.