作业帮y=-2(lg²x-3lgx) =-2(lgx-3/2)²+9/2 所以定义域是(0,+∞) 值域[[-∞,9/2] 怎么运算?我用几个公式都算不出来,如果正确,那么要怎么算?请您
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![y=-2(lg²x-3lgx) =-2(lgx-3/2)²+9/2 所以定义域是(0,+∞) 值域[[-∞,9/2] 怎么运算?我用几个公式都算不出来,如果正确,那么要怎么算?请您](/uploads/image/z/3138495-15-5.jpg?t=y%3D-2%28lg%26%23178%3Bx-3lgx%29+%3D-2%28lgx-3%2F2%29%26%23178%3B%2B9%2F2+%E6%89%80%E4%BB%A5%E5%AE%9A%E4%B9%89%E5%9F%9F%E6%98%AF%280%2C%2B%E2%88%9E%29+%E5%80%BC%E5%9F%9F%5B%5B-%E2%88%9E%2C9%2F2%5D+%E6%80%8E%E4%B9%88%E8%BF%90%E7%AE%97%3F%E6%88%91%E7%94%A8%E5%87%A0%E4%B8%AA%E5%85%AC%E5%BC%8F%E9%83%BD%E7%AE%97%E4%B8%8D%E5%87%BA%E6%9D%A5%2C%E5%A6%82%E6%9E%9C%E6%AD%A3%E7%A1%AE%2C%E9%82%A3%E4%B9%88%E8%A6%81%E6%80%8E%E4%B9%88%E7%AE%97%3F%E8%AF%B7%E6%82%A8)
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y=-2(lg²x-3lgx) =-2(lgx-3/2)²+9/2 所以定义域是(0,+∞) 值域[[-∞,9/2] 怎么运算?我用几个公式都算不出来,如果正确,那么要怎么算?请您
y=-2(lg²x-3lgx) =-2(lgx-3/2)²+9/2 所以定义域是(0,+∞) 值域[[-∞,9/2] 怎么运算?我用几个公式都算不出来,如果正确,那么要怎么算?请您
y=-2(lg²x-3lgx) =-2(lgx-3/2)²+9/2 所以定义域是(0,+∞) 值域[[-∞,9/2] 怎么运算?我用几个公式都算不出来,如果正确,那么要怎么算?请您
令a=lgx
则y=-2(a²-3a)
=-2(a²-3a+9/4-9/4)
=-2(a²-3a+9/4)+9/2
=-2(a-3/2)²+9/2
=-2(lgx-3/2)²+9/2