已知x+y=4,xy=7,则x²+y²=_,x²y+xy²_.

来源：学生作业帮编辑：作业帮分类：数学作业时间：2024/05/15 18:27:17

已知x+y=4,xy=7,则x²+y²=_____,x²y+xy²_____.
18b（a-b）²-12（b-a）三次方
x三次方-16xy²
18a-12ax+2ax²
x²-5x-24
am-2bm-2bm+an
（a²+4b²）²-16a²b²

1已知x+y=4,xy=7,则x²+y²=(x+y)²-2xy=16-14=2,x²y+xy²=xy(x+y)=4x7=28.
2:18b（a-b）²-12（b-a）^3
=18b(b-a)²-12(b-a)(b-a)²
=(b-a)²[18b-12(b-a)]
=(b-a)²(12a+6b)
=6(2a+b)(b-a)²
3:x^3-16xy²=x(x²-16y²)=x(x+4y)(x-4y)
4:18a-12ax+2ax²
=2a(x²-6x+9)
=2a(x-3)²
5:x²-5x-24
=(x-8)(x+3)
6:am-2bm-2bm+an
=a(m+n)-4bm
是不是
am-2bm-2bn+an
=a(m+n)-2b(m+n)
=(m+n)(a-2b)
7:（a²+4b²）²-16a²b²
=a^4+16b^4+8a²b²-16a²b²
=a^4+16b^4-8a²b²
=(a²-4b²)²

已知x²y²+x²+y²=10xy-16 求x,y 1.已知3x²-xy+y²=10,-xy+4y²=4,则x²-y²的值若4x²+4xy+2y²+6y+9=0,则x-y=_____ 已知xy=8满足x²y-xy²-x+y=56,求x²+y² 已知x/y=3,求x²+2xy-3y²/x²-2xy+y² 已知x/y=3,求x²+2xy-3y²/x²-xy+y²的值 xy²/(x²y-y) × x²/(x²+x)= xy²/(x²y) - y×x²/(x²+x)= 已知m=x²+y²/x²+y²,n=2xy/x²+y²,则下问已知x²+y²=7,xy=－2,求5x²-3xy-4y²-11xy-7x&su 1.已知x/y=3/4,求(7x²-3xy+2y²)/(2x²-3xy+7y²) 已知x/y=1/2,则x²-3xy+2y²/2x²-3xy+7y²