Question

求数学学霸解答

Answer 1

1. D

2. B

3. D

4. D

5. C

6. B

7. C

8. D
   

追问

还有

追答

9.-2x,8x
10.0
11.a^2b,3a^2b
12.5,-2
13.3.5
14.10a+8
15.47
16.3a^2b-10ab^2
17.-x
18.4,3
19.100(x-3)+10x+x-3
20.168x^13
21.
原式=12a^2b-6ab^2
=12×1/4×(-1)-6×1/2×(-1)^2
=-3-3
=-6

追问

追答

22.4a^2+4b^2-4c^2-12a^2+6b^2+9c^2
=-8a^2+10b^2+5c^2
23.2x^2+xy+3y^2-(x^2-xy)
=x^2+2xy+3y^2
24.原式=3xy+10y+5x-2xy-2y+3x
=xy+8(x+y)
=-2+24
=22
25.A-B=2a^2-4a+1-2a^2+4a-3=-2<0
A<B

追问

追答

26.m+1=4,m=3
2n=4,n=2
3m+2n=12

27.3x+2y+z=315
x+2y+3z=285
两式相加得4x+4y+4z=600
x+y+z=150
购甲乙丙各一件需150元

Answer 2

噢