分解因式：a^3-a,b^2（x-3)+b^2（3-x),16(m-n)^2-9(m+n)^2,4x^2(x-y)+(y

a^3-a=a(a^2-1)=a(a-1)(a+1)b^2（x-3)+b^2（3-x)=b^2(x-3)-b^2(x-3)=016(m-n)^2-9(m+n)^2=[4(m-n)-3(m+n)][4m-4n+3m+3n]=(4m-4n-3m-3n)(7m-n)=(m-7n)(7m-n)4x^2(x-y)+(y-x)=4x^2(x-y)-(x-y)=(4x^2-1)(x-y)=(2x-1)(2x+1)(x-y)4-x^2-4xy-4y^2=4-(x^2+4xy+4y^2)=4-(x+2y)^2=(2-x-2y)(2+x+2y)计算：(x-y+2)(x+y+2)=(x+2-y)(x+2+y)=(x+2)^2-y^2=x^2+4x+4-y^2(3x-2y-1)(3x+2y+1),=[3x-(2y+1)](3x+2y+1)=(3x)^2-(2y+1)^2=9x^2-4y^2-4y-1 -4x^3y*[7x^2y-3xy+(2xy)^3]= -4x^3y*xy(7x-3+8x^2y^2)= -4x^4y^2(7x-3+8x^2y^2)= -28x^5y^2+12x^4y^2-32x^6y^4x(2x+1)(1-2x)-4x(x-1)(1-x)=x[1-4x^2+4(x-1)^2]=x(1-4x^2+4x^2-8x+4)=x(1-8x+4)=x(5-8x)=5x-8x^2=5*(-1/2)-8*1/4=-2。5-2=-4。5y/3-y/2=1,式子二：2x+3y=-2(这题题目应该抄错了)m^2-2m+n^2+4n=-5m^2-2m+1+n^2+4n+4=0(m-1)^2+(n+2)^2=0∵(m-1)^2>=0 (n+2)^2>=0∴m=1 n=-2m+n=1-2=-1已知方程组3x+2y=m+2,2x+3y=m的解适合x+y=8,则m=?将3x+2y=m+2 2x+3y=m两边相加 得5x+5y=2m+2两边÷5x+y=2/5（m+1）∴2/5（m+1）=8m+1=20 m=19 题目有修改就HI我 我再补充答案!