1. 去括號(hào)：
(1)$4a - 2(b - 3c) = $
4a-2b+6c
；
(2)$-5a + \frac{1}{2}(4x - 6) = $
-5a+2x-3
；
(3)$3x + [4y - (7z + 3)] = $
3x+4y-7z-3
；
(4)$-3a^{3} - [2x^{2} - (5x + 1)] = $
-3a3-2x2+5x+1
。
答案：1.(1)4a-2b+6c (2)-5a+2x-3 (3)3x+4y-7z-3 (4)-3a3-2x2+5x+1
2. 添括號(hào)：
(1)$2 - x^{2} + 2xy - y^{2} = 2 - $(
x2-2xy+y2
)；
(2)$a - (b - c + d) = a - d + $(
-b+c
)；
(3)$5x + 3x^{2} - 4y^{2} = 5x - $(
4y2-3x2
)；
(4)$-3p + 3q - 1 = 3q - $(
3p+1
)。
答案：2.(1)x2-2xy+y2 (2)-b+c (3)4y2-3x2 (4)3p+1
解析：
(1)$x^{2}-2xy+y^{2}$
(2)$-b+c$
(3)$4y^{2}-3x^{2}$
(4)$3p+1$
3. 去括號(hào)并合并同類項(xiàng)：
(1)$a - (2a - 2)$； (2)$-(5x + y) - 3(2x - 3y)$；
(3)$2x^{2} - (7 + x) - x(3 + 4x)$； (4)$-(3a^{2} - 2a + 1) + (a^{2} - 5a + 7)$；
(5)$a^{2} - 3[a^{2} - 2(a^{2} - a) + 1]$； (6)$3a^{2}b - 2[ab^{2} - 2(a^{2}b - 2ab^{2})]$；
(7)$5a^{2} - [3a - (2a - 3) + 4a^{2}]$； (8)$2(a^{2}b - 3ab^{2}) - 3(2ab^{2} - \frac{5}{6}a^{2}b)$。
答案：3.(1)-a+2 (2)-11x+8y (3)-2x2-4x-7 (4)-2a2-3a+6 (5)4a2-6a-3 (6)7a2b-10ab2 (7)a2-a-3 (8)$\frac{9}{2}a2b-12ab2$
解析：
(1) $a - (2a - 2) = a - 2a + 2 = -a + 2$
(2) $-(5x + y) - 3(2x - 3y) = -5x - y - 6x + 9y = -11x + 8y$
(3) $2x^{2} - (7 + x) - x(3 + 4x) = 2x^{2} - 7 - x - 3x - 4x^{2} = -2x^{2} - 4x - 7$
(4) $-(3a^{2} - 2a + 1) + (a^{2} - 5a + 7) = -3a^{2} + 2a - 1 + a^{2} - 5a + 7 = -2a^{2} - 3a + 6$
(5) $a^{2} - 3[a^{2} - 2(a^{2} - a) + 1] = a^{2} - 3[a^{2} - 2a^{2} + 2a + 1] = a^{2} - 3[-a^{2} + 2a + 1] = a^{2} + 3a^{2} - 6a - 3 = 4a^{2} - 6a - 3$
(6) $3a^{2}b - 2[ab^{2} - 2(a^{2}b - 2ab^{2})] = 3a^{2}b - 2[ab^{2} - 2a^{2}b + 4ab^{2}] = 3a^{2}b - 2[5ab^{2} - 2a^{2}b] = 3a^{2}b - 10ab^{2} + 4a^{2}b = 7a^{2}b - 10ab^{2}$
(7) $5a^{2} - [3a - (2a - 3) + 4a^{2}] = 5a^{2} - [3a - 2a + 3 + 4a^{2}] = 5a^{2} - [a + 3 + 4a^{2}] = 5a^{2} - a - 3 - 4a^{2} = a^{2} - a - 3$
(8) $2(a^{2}b - 3ab^{2}) - 3(2ab^{2} - \frac{5}{6}a^{2}b) = 2a^{2}b - 6ab^{2} - 6ab^{2} + \frac{5}{2}a^{2}b = \frac{9}{2}a^{2}b - 12ab^{2}$
