已知整数x,y满足|lgx/y|≤1且|log(x²y)|≤1.求x,y的取值范围
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![已知整数x,y满足|lgx/y|≤1且|log(x²y)|≤1.求x,y的取值范围](/uploads/image/z/14835767-23-7.jpg?t=%E5%B7%B2%E7%9F%A5%E6%95%B4%E6%95%B0x%2Cy%E6%BB%A1%E8%B6%B3%7Clgx%2Fy%7C%E2%89%A41%E4%B8%94%7Clog%EF%BC%88x%26sup2%3By%EF%BC%89%7C%E2%89%A41.%E6%B1%82x%2Cy%E7%9A%84%E5%8F%96%E5%80%BC%E8%8C%83%E5%9B%B4)
已知整数x,y满足|lgx/y|≤1且|log(x²y)|≤1.求x,y的取值范围
已知整数x,y满足|lgx/y|≤1且|log(x²y)|≤1.求x,y的取值范围
已知整数x,y满足|lgx/y|≤1且|log(x²y)|≤1.求x,y的取值范围
由|lgx/y|≤1知 x>0, |log(x²y)|≤1知 x²y>0 y>0
|lgx/y|≤1 -1≤lgx/y≤1 -y≤lgx≤y
|log(x²y)|≤1 -1≤log(x²y)≤1 0.1≤ x²y≤10
y≤-lgx
y≥lgx
y≥1/(10x²)
y≤10/x²
x>0
y>0
画出四条曲线发现所得区域为一曲环,四条线的交点为其边界点
y=lgx
y=1/(10x²) 1=10yx²= 10x²lgx 10^(2y+1)y=1
y=lgx
y=10/x² 10=x²y=x²lgy 10^(2y-1)y=1
y=-lgx
y=1/(10x²) 1=10x²y=10x²(-lgx)=-10x²lgx 10^(1-2y)y=1
y=-lgx
y=10/x² 10=x²y=x²(-lgx)=-x²lgx 10^9(-1-2y)y=1