10道化簡求值題及答案,化簡求值題及答案40道

時間 2021-08-14 06:15:24

1樓:來一杯丞汁兒

3x-(-4y+9x)-[(-9y-12x)]其中y=9x=-10

2樓:凌月霜丶

1,3x'y-[2x'y-(2xyz-x'z)-4x'z]-xyz,其中x=-2,y=-3,z=1,

原式=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

當x=2,y=3,z=1時

原式=4*(-3)-2*3*1+3*4*1

=-12-6+12

=-62,3x+2y)+(4x+3y)其中x=5,y+3

原式=3x+2y+4x+3y=7x+5y

當x=5,y=3時

原式=5*7+(-3)*5+20

=35-15+20

=403,2x-3(2x-x)+(2y-y),其中x=1,y=2

解;原式=2x-3x+y

當x=1,y=2時

原式=2*1-3*1+2

=2-3+2

=14,(5a^2-3b^2)+(a^2+b^2)-(5a^2+3b^2),其中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

=-45,2(a^2b+ab^2)-2(a^2 b-1)-2ab^2 -2其中a=-2,b=2

=2a^2b+2ab^2-2a^2b+2-2ab^2-2

=0,6,a^2-ab+2b^2=3 求2ab-2a^2-4b^2-7的值

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,若a=2x^2+3xy-2x-3,b=-x^2+xy+2,且3a+6b的值與x無關,求y的值

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).其中x=-2

9x+6x² -3(x-2/3x²)

=9x+6x²-3x+2x²

=8x²+6x

=8×(-2)²+6×(-2)

=32-12

=209,1/4(-4x^2+2x-8)-(1/2x-1),其中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,其中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

=-611,(5a^2-3b^2)+(a^2+b^2)-(5a^2+3b^2),其中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

=-412、2(a^2b+ab^2)-2(a^2 b-1)-2ab^2 -2其中a=-2,b=2

=2a^2b+2ab^2-2a^2b+2-2ab^2-2

=013、(x-2分之1y-1)(x-2分之1y+1)-(x-2分之1y-1)的平方,其中x=1.7,y=3.9

[(x-2分之1y)-1][(x+2分之1y)+1]-(x-2分之1y-1)平方

=(x+2分之1y)平方-1-(x-2分之1y)平方+2(x-2分之1y)-1

=(x+2分之1y)平方-(x-2分之1y)平方+2(x-2分之1y)-2

=2xy+2x-y-2

=3.9*2.4+1.4

=10.76

14,2a-(3a-2b+2)+(3a-4b-1),其中a=5 b=-3

=2a-3a+2b-2+3a-4b-1

=(2-3+3)a+(2-4)b+(-2-1)

=2a-2b-3

=10-(-6)-3

=10+6-3

=1315,5-(1-x)-1-(x-1)-2x+(-5y),其中x=2,y=2x

=4-2x-5y

=4-4-20

=-20

16,2x-(x+3y)-(-x-y)-(x-y),其中x=3,y=-3

=2x-x+3y+x+y-x+y

=x+5y

=3-15

=-12

17,-ab+3ba-(-2ab),其中a=2,b=1

=-ab+3ba+2ab

=2ab+2ab

=4ab

=4*2*1

=818,-m-[-(2m-3n)]+[-(-3m)-4n],其中m=2,n=1

=-m-(-2m+3n)+3m-4n

=-m-4m+2m-3n+3m

=-3n

=-3*1

=-319,2(2a+2ab)-2(2ab-1)-2ab-2,其中a=-2 b=2

=4a+4ab-4ab+2-2ab-2

=4a-2ab

=4*(-2)-2*(-2)*2

=-8-(-8)

=8+8

=020,3ab-4ab+8ab-7ab+ab,其中a=-2,b=3

=-8ab+9ab

=ab=-2*3=-6

3樓:

a=x^2-2x^2+4x+3, b=x^2+2x-6,求a-b其中x=1

解 原式=x^2-2x^2+4x+3-x^2-2x+6=-2x^2+2x+9

因為x=1

所以a-b=9

4樓:prince孫雨彤

題目在**?**都沒有

化簡求值題及答案40道

5樓:飽讀詩書丶

化簡求值題及答案推薦如下:

1、已知a,b是方程x^2+2x-5=0的兩個實數根,

求(a^2+2ab+2a)(b^2+2ab+2b)的值.

由a,b是方程x^2+2x-5=0的兩個實數根得:

ab=-5,a+b=-2

a^2+2ab+2a)(b^2+2ab+2b)

=ab(a+2b+2)(b+2a+2)

=-5(-2+b+2)(-2+a+2)

=-5ab

=252、1/2(x+y+z)方+1/2(x-y-z)(x-y+z)-z(x+y),其中x-y=6,xy=21.要詳細步驟

化簡得:

1/2(x+y+z)方+1/2(x-y-z)(x-y+z)-z(x+y)=

1/2[(x+y)方+2z(x+y)+z方]+1/2[(x-y)方-z方]-z(x+y)=

1/2(x+y)方+1/2(x-y)方=x方+y方

由x-y=6,xy=21得,x方+y方=(x-y)方+2xy=78

3、a^2-ab+2b^2=3 求2ab-2a^2-4b^2-7的值

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

4、若a=2x^2+3xy-2x-3,b=-x^2+xy+2,且3a+6b的值與x無關,求y的值

解: 3a+6b=6x^2+9xy-6x-9-6x^2+6xy+12

=15xy-6x+3

=x(15y-6)+3

5、9x+6x^2 -3(x-2/3x^2).其中x=-2

9x+6x² -3(x-2/3x²)

=9x+6x²-3x+2x²

=8x²+6x

=8×(-2)²+6×(-2)

=32-12

=206、1/4(-4x^2+2x-8)-(1/2x-1),其中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

7、3x'y-[2x'y-(2xyz-x'z)-4x'z]-xyz,其中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

6樓:凌月霜丶

^1,3x'y-[2x'y-(2xyz-x'z)-4x'z]-xyz,其中x=-2,y=-3,z=1,

原式=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

當x=2,y=3,z=1時

原式=4*(-3)-2*3*1+3*4*1

=-12-6+12

=-62,3x+2y)+(4x+3y)其中x=5,y+3

原式=3x+2y+4x+3y=7x+5y

當x=5,y=3時

原式=5*7+(-3)*5+20

=35-15+20

=403,2x-3(2x-x)+(2y-y),其中x=1,y=2

解;原式=2x-3x+y

當x=1,y=2時

原式=2*1-3*1+2

=2-3+2

=14,(5a^2-3b^2)+(a^2+b^2)-(5a^2+3b^2),其中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

=-45,2(a^2b+ab^2)-2(a^2 b-1)-2ab^2 -2其中a=-2,b=2

=2a^2b+2ab^2-2a^2b+2-2ab^2-2

=0,6,a^2-ab+2b^2=3 求2ab-2a^2-4b^2-7的值

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,若a=2x^2+3xy-2x-3,b=-x^2+xy+2,且3a+6b的值與x無關,求y的值

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).其中x=-2

9x+6x² -3(x-2/3x²)

=9x+6x²-3x+2x²

=8x²+6x

=8×(-2)²+6×(-2)

=32-12

=209,1/4(-4x^2+2x-8)-(1/2x-1),其中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,其中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

=-611,(5a^2-3b^2)+(a^2+b^2)-(5a^2+3b^2),其中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

=-412、2(a^2b+ab^2)-2(a^2 b-1)-2ab^2 -2其中a=-2,b=2

=2a^2b+2ab^2-2a^2b+2-2ab^2-2

=013、(x-2分之1y-1)(x-2分之1y+1)-(x-2分之1y-1)的平方,其中x=1.7,y=3.9

[(x-2分之1y)-1][(x+2分之1y)+1]-(x-2分之1y-1)平方

=(x+2分之1y)平方-1-(x-2分之1y)平方+2(x-2分之1y)-1

=(x+2分之1y)平方-(x-2分之1y)平方+2(x-2分之1y)-2

=2xy+2x-y-2

=3.9*2.4+1.4

=10.76

14,2a-(3a-2b+2)+(3a-4b-1),其中a=5 b=-3

=2a-3a+2b-2+3a-4b-1

=(2-3+3)a+(2-4)b+(-2-1)

=2a-2b-3

=10-(-6)-3

=10+6-3

=1315,5-(1-x)-1-(x-1)-2x+(-5y),其中x=2,y=2x

=4-2x-5y

=4-4-20

=-20

16,2x-(x+3y)-(-x-y)-(x-y),其中x=3,y=-3

=2x-x+3y+x+y-x+y

=x+5y

=3-15

=-12

17,-ab+3ba-(-2ab),其中a=2,b=1

=-ab+3ba+2ab

=2ab+2ab

=4ab

=4*2*1

=818,-m-[-(2m-3n)]+[-(-3m)-4n],其中m=2,n=1

=-m-(-2m+3n)+3m-4n

=-m-4m+2m-3n+3m

=-3n

=-3*1

=-319,2(2a+2ab)-2(2ab-1)-2ab-2,其中a=-2 b=2

=4a+4ab-4ab+2-2ab-2

=4a-2ab

=4*(-2)-2*(-2)*2

=-8-(-8)

=8+8

=020,3ab-4ab+8ab-7ab+ab,其中a=-2,b=3

=-8ab+9ab

=ab=-2*3=-6

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