Question

求初一几道代数式去括号运算。请保证全对。

一、去括号计算
<1>5a-(2a-4b)
<2>2xˆ2+3(2x-xˆ2)-2(-xˆ2+3x)
<3>3xˆ2-[xˆ2+2(xy-2yˆ2)+4yˆ2]+2xy
<4>a-(-b-c+d)
<5>a-(b-c+d)
<6>3a-2(b-3c)
<7>(8x-5y)-(4x-9y)
<8>-3aˆ3-[2xˆ2-(5x+1)]
<9>4x-(-5x+3x-6)
<10>(2m-3)+m-(3m-2)
<11>3(4x-2y)-3(-y+8x)
<12>3aˆ2-2[2aˆ2-(2ab-aˆ2)+4ab]
<13>2a+(5a-3b)-(a+2b)
<14>-3+(-xˆ2+4x)-(-8+3xˆ2)
<15>9aˆ2+[7aˆ2-(2a-aˆ2)-3a]
<16>-0.5(4xy-8xˆ2yˆ2)+1/3(xy-6xˆ2yˆ2)

Answer 1

<1>5a-(2a-4b)=5a-2a+4b=3a+4b

<2>2xˆ2+3(2x-xˆ2)-2(-xˆ2+3x)=2x²+6x-3x²+2x²-6x=x²

<3>3xˆ2-[xˆ2+2(xy-2yˆ2)+4yˆ2]+2xy=3x²-x²-2xy+4y²-4y²+2xy=2x²

<4>a-(-b-c+d)=a+b+c-d

<5>a-(b-c+d)=a-b+c-d

<6>3a-2(b-3c)=3a-2b+6c

<7>(8x-5y)-(4x-9y)=8x-5y-4x+9y=4x+4y

<8>-3aˆ3-[2xˆ2-(5x+1)]=-3a³-2x²+5x+1

<9>4x-(-5x+3x-6)=4x+5x-3x+6=6x+6

<10>(2m-3)+m-(3m-2)=2m-3+m-3m+2=-1

<11>3(4x-2y)-3(-y+8x)=12x-6y+3y-24x=-12x-3y

<12>3aˆ2-2[2aˆ2-(2ab-aˆ2)+4ab]
=3a²-2(2a²-2ab+a²+4ab)=3a²-2(3a²+2ab)=3a²-6a²-4ab=-3a²-4ab

<13>2a+(5a-3b)-(a+2b)=2a+5a-3b-a-2b=6a-5b

<14>-3+(-xˆ2+4x)-(-8+3xˆ2)=-3-x²+4x+8-3x²=-4x²+4x+5

<15>9aˆ2+[7aˆ2-(2a-aˆ2)-3a]=9a²+7a²-2a+a²-3a=16a²-5a

<16>-0.5(4xy-8xˆ2yˆ2)+1/3(xy-6xˆ2yˆ2)=-2xy+4x²y²+1/3xy-2x²y²=2x²y²-5/3xy

Answer 2

<1>5a-(2a-4b)
=5a-2a+4b
=3a+4b

<2>2x^2+3(2x-x^2)-2(-x^2+3x)
=2x^2+6x-3x^2+2x^2-6x
=2x^2+2x^2-3x^2+6x-6x
=x^2

<3>3x^2-[x^2+2(xy-2y^2)+4y^2]+2xy
=3x^2-[x^2+2xy-4y^2+4y^2]+2xy
=3x^2-[x^2+2xy]+2xy
=3x^2-x^2-2xy+2xy
=x^2

<4>a-(-b-c+d)
=a+b+c-d

<5>a-(b-c+d)
=a-b+c-d

<6>3a-2(b-3c)
=3a-2b+6c

<7>(8x-5y)-(4x-9y)
=8x-5y-4x+9y
=8x-4x+9y-5y
=4x+4y

<8>-3a^3-[2x^2-(5x+1)]
=-3a^3-[2x^2-5x-1]
=-3a^3-2x^2+5x+1

<9>4x-(-5x+3x-6)
=4x+5x-3x+6
=6x-6

<10>(2m-3)+m-(3m-2)
=2m-3+m-3m+2
=2m+m-3m+2-3
=-1

<11>3(4x-2y)-3(-y+8x)
=12x-6y+3y-24x
=12x-24x-6y+3y
=-12x-3y

<12>3a^2-2[2a^2-(2ab-a^2)+4ab]
=3a^2-2[2a^2-2ab+a^2+4ab]
=3a^2-2[2a^2+a^2-2ab+4ab]
=3a^2-2[3a^2+2ab]
=3a^2-6a^2-4ab
=-3a^2-4ab

<13>2a+(5a-3b)-(a+2b)
=2a+5a-3b-a-2b
=2a+5a-a-2b-3b
=6a-5b

<14>-3+(-x^2+4x)-(-8+3x^2)
=-3-x^2+4x+8-3x^2
=-x^2-3x^2+4x+8-3
=-4x^2+4x+5

<15>9a^2+[7a^2-(2a-a^2)-3a]
=9a^2+7a^2-(2a-a^2)-3a
=9a^2+7a^2-2a+a^2-3a
=9a^2+7a^2+a^2-2a-3a
=17a^2-5a

<16>-0.5(4xy-8x^2y^2)+1/3(xy-6x^2y^2)
=-2xy+4x^2y^2+1/3*xy-2x^2y^2
=4x^2y^2-2x^2y^2+1/3*xy-2xy
=2x^2y^2-5/3*xy

追问

谢谢您的回答。不过，您的和似乎计算有误。望改正。
谢谢。

Answer 3

我会做，但是需要时间