作业帮16y^2-*64y
来源：学生作业帮助网 编辑：作业帮 时间：2024/05/10 14:02:19
第一种：用平方差公式,原式=(x+y)^2-(4(x-y))^2=(x+y-4(x-y))(x+y+4(x-y))=(5y-3x)(5x-3y)第二种：全展开合并同类项,原式=x^2+y^2+2xy-16(x^2+y^2-2xy)=-15x
答：(y²-5y-2)(y²-5y-4)-16=(y²-5y)²-6(y²-5y)+8-16=(y²-5y)²-6(y²-5y)-8=(y²-5y-3
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2y''+y'-y=0特征方程：2r^2+r-1=0根为：-1,1/2y=C1e^(-x)+C2e^(x/2)
（1）x2（x-y）+y2（y-x）=（x-y）（x2-y2）=（x-y）2（x+y）；（2）（x+y）2+64-16（x+y）=（x+y-8）2．
解（y^2+y-2）/（y^2+4y+4）=（y+2）（y-1）/(y+2)^2=（y-1）/(y+2)
移项、得1.5y=-3系数化为一、y=-2很简单的呀
∫[(sin1/y)/y^2]dy令u=1/ydu=(-1/y^2)dy原式=∫-sinudu=cosu+C=cos(1/y)+C
∵（2y+3）（3y+2）-6y（y+3）+5y+16=6y2+4y+9y+6-6y2-18y+5y+16=22∴（2y+3）（3y+2）-6y（y+3）+5y+16的值与y的值无关．
[(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y=[x²-y²-x²-2xy-y²-xy+xy²]/(y/2)=[(x-2)y²-3xy]/(y/2)=2x
(x-y)(z+y-x+y+2y)÷4y=(x-y)(z-x+4y)÷4y{(x+y)(x-y)-(x-y)的2次方+2y(x-y)}除以4y=(x-y)(x+y-x+y+2y)÷4y=(x-y)(4y)÷4y=x-y
第一题：原式=25(x-2y)^2-16(2x+y)^2=（5x-10y)^2-(8x+4y)^2=(5x-10y+8x+4y)(5x-10y-8x-4y)后面自己做啦.第二题：原式=m(4m^2-9n^2)=m(2m+3n)(2m-3n)
16(x+y)^2-25(x-y)^2=[4﹙x＋y﹚＋5﹙x－y﹚][4﹙x＋y﹚－5﹙x－y﹚]=﹙9x－y﹚﹙9y－x﹚
25(x+y)^2-16(x-y)^2=[5(x+y)+4(x-y)][5(x+y)-4(x-y)]=(9x+y)(x+9y)
16(x-y)^2-9(x+y)^2=(4x-4y)²-(3x+3y)²=(4x-4y+3x+3y)(4x-4y-3x-3y)=(7x-y)(x-7y)
=(x-y)^2-2*4(x-y)+4^2=(x-y-4)^2
(x+y)的平方+2*4(x+y)+4的平方(x+y)=(x+y+4)的平方
6y-(y+2分之y+2-y分之y)除以y³-4y-2y²+8分之y=6y-[(2y-y²+2y+y²)/(4-y²)]÷y/(y-2)³=6y+[4y/(y-2)(y+2)]÷y
(x+2y)^2-2(x+2y)(x-2y)+(x-2y)^2=16y[(x+2y)-(x-2y)]²=16y16y²=16yy²-y=0,y(y-1)=0y1=0,xy都不等于0,舍去;y2-1=0,y2=1