点P(2,3)到直线ax+(a-1)y+3=0的距离等于3,则a=
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![点P(2,3)到直线ax+(a-1)y+3=0的距离等于3,则a=](/uploads/image/z/8781435-27-5.jpg?t=%E7%82%B9P%EF%BC%882%2C3%EF%BC%89%E5%88%B0%E7%9B%B4%E7%BA%BFax%2B%28a-1%29y%2B3%3D0%E7%9A%84%E8%B7%9D%E7%A6%BB%E7%AD%89%E4%BA%8E3%2C%E5%88%99a%3D)
点P(2,3)到直线ax+(a-1)y+3=0的距离等于3,则a=
点P(2,3)到直线ax+(a-1)y+3=0的距离等于3,则a=
点P(2,3)到直线ax+(a-1)y+3=0的距离等于3,则a=
距离d=|2a+3(a-1)+3|/√[a²+(a-1)²]=3
|5a|=3√(2a²-2a+1)
平方
25a²=18a²-18a+9
7a²+18a-9=0
a=3/7,a=-3
|2a+3(a-1)+3|/√[a^2+(a-1)^2]=3
|5a|=3√(2a^2-2a+1)
平方得
25a^2=18a^2-18a+9
7a^2+18a-9=0
(a+3)(7a-3)=0
a=-3或a=3/7