1,3x'y-[2x'y-(2xyz-x'z)-4x'z]-xyz,å
¶ä¸x=-2,y=-3,z=1,
åå¼=3x'y-[2x'y-(2xyz-x'z)-4x'z]-xyz
=3x'y-2x'y+2xyz-x'z+4x'z-xyz
=x'y-xyz+3x'z
å½x=2,y=3,z=1æ¶
åå¼=4*(-3)-2*3*1+3*4*1
=-12-6+12
=-6
2,3X+2Y)+(4X+3Y)å
¶ä¸X=5,Y+3
åå¼=3X+2Y+4X+3Y=7X+5Y
å½X=5,Y=3æ¶
åå¼=5*7+ï¼-3ï¼*5+20
=35-15+20
=40
3,2x-3(2x-x)+(2y-y),å
¶ä¸x=1,y=2
解ï¼åå¼=2x-3x+y
å½x=1,y=2æ¶
åå¼=2*1-3*1+2
=2-3+2
=1
4,(5a^2-3b^2)+(a^2+b^2)-(5a^2+3b^2),å
¶ä¸a=-1,b=1
=5a^2-3b^2+a^2+b^2-5a^2-3b^2
=a^2-5b^2
=(-1)^2-5*1^2
=1-5
=-4
5,2(a^2b+ab^2)-2(a^2 b-1)-2ab^2 -2å
¶ä¸a=-2,b=2
=2a^2b+2ab^2-2a^2b+2-2ab^2-2
=0,
6,a^2-ab+2b^2=3 æ±2ab-2a^2-4b^2-7çå¼
2ab-2a^2-4b^2-7
=2(ab-a^2-2b^2)-7
=-2(a^2-ab+2b^2)-7
=(-2)*3-7
=-6-7
=-13
7,è¥A=2x^2+3xy-2x-3,B=-x^2+xy+2,ä¸3A+6Bçå¼ä¸xæ å
³,æ±yçå¼
3A+6B=6x^2+9xy-6x-9-6x^2+6xy+12
=15xy-6x+3
=x(15y-6)+3
8,x+6x^2 -3(x-2/3x^2).å
¶ä¸x=-2
9x+6x² -3(x-2/3x²)
=9x+6x²-3x+2x²
=8x²+6x
=8Ã(-2)²+6Ã(-2)
=32-12
=20
9,1/4(-4x^2+2x-8)-(1/2x-1),å
¶ä¸x=1/2
1/4(-4x²+2x-8)-(1/2x-1)
=-x²+1/2x-2-1/2x+1
=-x²-1
=-(1/2)²-1
=-1/4-1
=-5/4,
10,3x'y-[2x'y-(2xyz-x'z)-4x'z]-xyz,å
¶ä¸x=-2,y=-3,z=1,
:3x'y-[2x'y-(2xyz-x'z)-4x'z]-xyz
=3x'y-2x'y+2xyz-x'z+4x'z-xyz
=x'y-xyz+3x'z
=4*(-3)-2*3*1+3*4*1
=-12-6+12
=-6
11,(5a^2-3b^2)+(a^2+b^2)-(5a^2+3b^2),å
¶ä¸a=-1,b=1
=5a^2-3b^2+a^2+b^2-5a^2-3b^2
=a^2-5b^2
=(-1)^2-5*1^2
=1-5
=-4
12ã2(a^2b+ab^2)-2(a^2 b-1)-2ab^2 -2å
¶ä¸a=-2,b=2
=2a^2b+2ab^2-2a^2b+2-2ab^2-2
=0
13ã(X-2åä¹1Y-1)(X-2åä¹1Y+1)-(X-2åä¹1Y-1)çå¹³æ¹,å
¶ä¸X=1.7,Y=3.9
[(X-2åä¹1Y)-1][(X+2åä¹1Y)+1]-(X-2åä¹1Y-1)å¹³æ¹
=(X+2åä¹1Y)å¹³æ¹-1-(X-2åä¹1Y)å¹³æ¹+2(X-2åä¹1Y)-1
=(X+2åä¹1Y)å¹³æ¹-(X-2åä¹1Y)å¹³æ¹+2(X-2åä¹1Y)-2
=2XY+2X-Y-2
=3.9*2.4+1.4
=10.76
14,2a-ï¼3a-2b+2ï¼+ï¼3a-4b-1),å
¶ä¸a=5 b=-3
=2a-3a+2b-2+3a-4b-1
=ï¼2-3+3ï¼a+ï¼2-4ï¼b+ï¼-2-1ï¼
=2a-2b-3
=10-(-6)-3
=10+6-3
=13
15,5-(1-x)-1-(x-1ï¼-2x+(-5yï¼,å
¶ä¸x=2,y=2x
=4-2x-5y
=4-4-20
=-20
16,2x-(x+3y)-(-x-y)-(x-y),å
¶ä¸x=3,y=-3
=2x-x+3y+x+y-x+y
=x+5y
=3-15
=-12
17,-ab+3ba-(-2ab),å
¶ä¸a=2,b=1
=-ab+3ba+2ab
=2ab+2ab
=4ab
=4*2*1
=8
18,-m-[-(2m-3n)]+[-(-3m)-4n],å
¶ä¸m=2,n=1
=-m-(-2m+3n)+3m-4n
=-m-4m+2m-3n+3m
=-3n
=-3*1
=-3
19,2ï¼2a+2ab)-2(2ab-1)-2ab-2,å
¶ä¸a=-2 b=2
=4a+4ab-4ab+2-2ab-2
=4a-2ab
=4*(-2)-2*(-2)*2
=-8-(-8)
=8+8
=0
20,3ab-4ab+8ab-7ab+ab,å
¶ä¸a=-2,b=3
=-8ab+9ab
=ab
=-2*3
=-6
温馨提示:内容为网友见解,仅供参考