已知x+y=6,xy=7,求值:1.x²+y²,2.x²-xy+y² 3.x
来源:学生作业帮 编辑:搜狗做题网作业帮 分类:数学作业 时间:2024/06/25 03:02:54
已知x+y=6,xy=7,求值:1.x²+y²,2.x²-xy+y² 3.x²y+xy² 4.x-y
上面的平方可能会变成2,所以重新打了一遍..
上面的平方可能会变成2,所以重新打了一遍..
![已知x+y=6,xy=7,求值:1.x²+y²,2.x²-xy+y² 3.x](/uploads/image/z/17735951-47-1.jpg?t=%E5%B7%B2%E7%9F%A5x%2By%3D6%2Cxy%3D7%2C%E6%B1%82%E5%80%BC%EF%BC%9A1.x%26%23178%3B%2By%26%23178%3B%2C2.x%26%23178%3B-xy%2By%26%23178%3B+3.x%26%23)
x²+y²
= x²+y²+2xy-2xy
= (x+y)² -2xy
= 6²-2×7
= 36-14
= 22
x²-xy+y²
= x²+y²+2xy-3xy
= (x+y)² -3xy
= 6² -3×7
= 36-21
= 15
x²y+xy²
= xy(x+y)
= 7×6
= 42
因为 x+y=6,xy=7,可得 x,y都是正数
又 (x-y)² = (x+y)² -4xy = 6²-4×7 = 36-28 = 8
所以 x-y = √8 = 2√2
--------------------
梳理知识,帮助别人,愉悦自己.
“数理无限”团队欢迎你
= x²+y²+2xy-2xy
= (x+y)² -2xy
= 6²-2×7
= 36-14
= 22
x²-xy+y²
= x²+y²+2xy-3xy
= (x+y)² -3xy
= 6² -3×7
= 36-21
= 15
x²y+xy²
= xy(x+y)
= 7×6
= 42
因为 x+y=6,xy=7,可得 x,y都是正数
又 (x-y)² = (x+y)² -4xy = 6²-4×7 = 36-28 = 8
所以 x-y = √8 = 2√2
--------------------
梳理知识,帮助别人,愉悦自己.
“数理无限”团队欢迎你
已知x²+y²-8x+6y+25=0,求(x-y+4xy/x-y)(x+y-4xy/x+y)
分式的化简求值已知x/y=2求x²-xy+3y²/x²+xy+6y²
先化简,再求值:4x²y-【6xy-2(4xy-2)-xy²】+1.其中x=-二分之一,y=2.
化简求值:(x+y)(x-y)+(x-y)²-(6x²y-2xy²)÷2y,其中x=-2,
化简求值3x²y-[2xy-2(xy-3/2x²y)+xy]+3xy²其中x=3、y=-1
x²/xy-x/y
1.化简求值:(x+y)(x-y)-(x-y)²-6x²y÷2y+(2xy)²÷(-4xy
已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y²
化简求值(xy-x²)/xy分之x²-2xy+y²乘x²分之x-y,其中y=二分
先化简再求值,3xy²(xy+2y²-x²)+3x³y²,其中x=2,
已知x+y=1,xy=-二分之一,求x(x+y)(x-y)-x(x+y)²
计算:(xy-x²)×x-y/xy