已知x+y=8,xy=12,求x²y+xy²的值解方程①(x+7)(x+5)-(x+1)(x+5)=42②(3x-5)²-(3x+7)²=0

已知x+y=8,xy=12,求x²y+xy²的值解方程①(x+7)(x+5)-(x+1)(x+5)=42②(3x-5)²-(3x+7)²=0
已知x+y=8,xy=12,求x²y+xy²的值
解方程①(x+7)(x+5)-(x+1)(x+5)=42
②(3x-5)²-(3x+7)²=0

已知x+y=8,xy=12,求x²y+xy²的值解方程①(x+7)(x+5)-(x+1)(x+5)=42②(3x-5)²-(3x+7)²=0
x²y+xy²
=xy(x+y)
=12x8
96
①(x+7)(x+5)-(x+1)(x+5)=42
x²+12x+35-x²-6x-5=42
6x+30=42
6x=12
x=2
②(3x-5)²-(3x+7)²=0
(3x-5+3x+7)(3x-5-3x-7)=0
-12(6x+2)=0
3x+1=0
x=-1/3
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已知x+y=8,xy=12，求x²y+xy²的值
x²y+xy²=xy(x+y)=12×8=96
解方程①(x+7)(x+5)-(x+1)(x+5)=42
x²+12x+35-x²-6x-5-42=0
6x-12=0
x=2
②(3x-5)²-(3x+7)²=0
(3x-5+3x+7)(3x-5-3x-7)=0
-12(6x+2)=0
3x+1=0
x= -1/3

x^2y+xy^2=xy(x+y)=12*8=96
提取(x+5)(x+7-x-1)=42 (x+5)6=42 x=2
(3x-5+3x+7)(3x-5-3x-7)=0 -12*(6x+2)=0 x=-1/3