跪求10道代数式求值化简,谢谢,初一难度,谢谢,不要网上的,谢谢.
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(3X+2Y)+(4X+3Y)其中X=5,Y+3解:原式=3X+2Y+4X+3Y=7X+5Y当X=5,Y=3时原式=5*7+(-3)*5+202.(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=-43.2(a^2b+ab^2)-2(a^2b-1)-2ab^2-2其中a=-2,b=2=2a^2b+2ab^2-2a^2b+2-2ab^2-2=01、已知A,B是方程x^2+2x-5=0的两个实数根,求(A^2+2AB+2A)(B^2+2AB+2B)的值.由A,B是方程x^2+2x-5=0的两个实数根得:AB=-5,A+B=-2A^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.要详细步骤化简得: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=783、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=-134、若A=2x^2+3xy-2x-3,B=-x^2+xy+2,且3A+6B的值与x无关,求y的值解:3A+6B=6x^2+9xy-6x-9-6x^2+6xy+12=15xy-6x+3=x(15y-6)+35、9x+6x^2-3(x-2/3x^2).其中x=-29x+6x??-3(x-2/3x??)=9x+6x??-3x+2x??=8x??+6x=8×(-2)??+6×(-2)=32-12=206、1/4(-4x^2+2x-8)-(1/2x-1),其中x=1/21/4(-4x??+2x-8)-(1/2x-1)=-x??+1/2x-2-1/2x+1=-x??-1=-(1/2)??-1=-1/4-1=-5/47、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=-68、(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=-49、2(a^2b+ab^2)-2(a^2b-1)-2ab^2-2其中a=-2,b=2=2a^2b+2ab^2-2a^2b+2-2ab^2-2=010、(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(先化简再求值)[(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=10.761、已知A,B是方程x^2+2x-5=0的两个实数根,求(A^2+2AB+2A)(B^2+2AB+2B)的值.由A,B是方程x^2+2x-5=0的两个实数根得:AB=-5,A+B=-2A^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.要详细步骤化简得: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=783、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=-134、若A=2x^2+3xy-2x-3,B=-x^2+xy+2,且3A+6B的值与x无关,求y的值解:3A+6B=6x^2+9xy-6x-9-6x^2+6xy+12=15xy-6x+3=x(15y-6)+35、9x+6x^2-3(x-2/3x^2).其中x=-29x+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=1/21/4(-4x²+2x-8)-(1/2x-1)=-x²+1/2x-2-1/2x+1=-x²-1=-(1/2)²-1=-1/4-1=-5/47、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=-68、(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=-49、2(a^2b+ab^2)-2(a^2b-1)-2ab^2-2其中a=-2,b=2=2a^2b+2ab^2-2a^2b+2-2ab^2-2=010、(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(先化简再求值)[(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=10.7611.(3X+2Y)+(4X+3Y)其中X=5,Y+3解:原式=3X+2Y+4X+3Y=7X+5Y当X=5,Y=3时原式=5*7+(-3)*5+2012.(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=-413.2(a^2b+ab^2)-2(a^2b-1)-2ab^2-2其中a=-2,b=2=2a^2b+2ab^2-2a^2b+2-2ab^2-2=014.2a-(3a-2b+2)+(3a-4b-1)=( ),a=b=1=2a-3a+2b-2+3a-4b-1=(2-3+3)a+(2-4)b+(-2-1)=2a-2b-3=-315.5-(1-x)-1-(x-1),x=11=5-1+x-1-x+1=4③2x-(x+3y)-(-x-y)-(x-y)=( )=2x-x+3y+x+y-x+y=x+5ya=2,b=4求2(a-b-54)+3(a+b)=5a+b-108=5*2+4-108=-94a=b=1求a+b-2(a-b+1)=-a+3b-2=-1+3-2=026.-(2x2-y2)-[2y2-(x2+2xy)]=______.27.若-3a3b2与5ax-1by+2是同类项,则x=______,y=______.28.(-y+6+3y4-y3)-(2y2-3y3+y4-7)=______.29.化简代数式4x2-[7x2-5x-3(1-2x+x2)]的结果是______.30.2a-b2+c-d3=2a+()-d3=2a-d3-()=c-().31.3a-(2a-3b)+3(a-2b)-b=______.32.化简代数式x-[y-2x-(x+y)]等于______.33.[5a2+()a-7]+[()a2-4a+()]=a2+2a+1.34.3x-[y-(2x+y)]=______.35.化简|1-x+y|-|x-y|(其中x<0,y>0)等于______.36.已知x≤y,x+y-|x-y|=______.37.已知x<0,y<0,化简|x+y|-|5-x-y|=______.38.4a2n-an-(3an-2a2n)=______.39.若一个多项式加上-3x2y+2x2-3xy-4得2x2y+3xy2-x2+2xy,则这个多项式为______.40.-5xm-xm-(-7xm)+(-3xm)=______.41.当a=-1,b=-2时,[a-(b-c)]-[-b-(-c-a)]=______.43.当a=-1,b=1,c=-1时,-[b-2(-5a)]-(-3b+5c)=______.44.-2(3x+z)-(-6x)+(-5y+3z)=______.45.-5an-an+1-(-7an+1)+(-3an)=______.46.3a-(2a-4b-6c)+3(-2c+2b)=______.48.9a2+[7a2-2a-(-a2+3a)]=______.50.当2y-x=5时,5(x-2y)2-3(-x+2y)-100=______.
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