化简求值的数学题！很长喔

Question

第一题：5abc-｛2a的平方-【3ab-(4ab的平方-a的平方b）】｝其中a=-2，b=-1，c=3

第二题：-（3a-4）-（a的平方-3a+5）+（4a-a的平方）其中a=-3分之一
5abc-｛2a的平方b-【3ab-(4ab的平方-a的平方b）】｝其中a=-2，b=-1，c=3

Answer 1

5abc-｛2a^2-[3ab-(4ab^2-a^2b)]｝
=5abc-2a^2b+[3ab-(4ab^2-a^2b)]
=5abc-2a^2b+3ab-(4ab^2-a^2b)
=5abc-a^2b+3ab-4ab^2
=30+4+6+8
=48

-(3a-4)-(a^2-3a+5)+(4a-a^2)
=-3a+4-a^2+3a-5+4a-a^2
=-1-2a^2+4a
=-1-2*(1/9)-4*1/3
=-23/9

Answer 2

1.解：
5abc-{2a²-[3ab-（4ab²-a²b)]}
=5abc-{2a²-[3ab-4ab²+a²b]}
=5abc-{2a²-3ab+4ab²-a²b}
=5abc-2a²+3ab-4ab²+a²b

当a=-2，b=-1，c=3时

5abc-2a²+3ab-4ab²+a²b
=5×-2×-1×3-2×（-2）²+3×-2×-1-4×-2×（-1）²+（-2）²-1
=30-2×4+6-4×-2×1+4-1
=30-8+6-（-8）+3
=28+8+3
=39

2.解：-（3a-4）-（a²-3a+5）+（4a-a²）
=-3a+4-a²+3a-5+4a-a²
=-2a²-1

当a=-1/3

Answer 3

5abc-｛2a^2-[3ab-(4ab^2-a^2b)]｝
=5abc-2a^2b+[3ab-(4ab^2-a^2b)]
=5abc-2a^2b+3ab-(4ab^2-a^2b)
=5abc-a^2b+3ab-4ab^+2
=30+4+6+8
=48

-(3a-4)-(a^2-3a+5)+(4a-a^2)
=-3a+4-a^2+3a-5+4a-a^2
=-1-2a^2+4a
=-1-2*(1/9)-4*1/3
=-23/9

呵呵，我刷分