更新1:
我唔明點由2個等於变成一個等於...
更新2:
If a and b are the roots of the equation 2x^2-5x+4=0, find the values of a. 2a+2b b. (a-1)(b-1) c. a^2+b^2 d. (a-b^2)
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回答 (2)
2009-08-31 3:39 am
✔ 最佳答案
Let y=5^x, then the equation becomesy^2-10y+25=0
(y-5)^2=0
y=5
5^x=5
x=1
2009-08-31 4:29 am
設y =5^x
y^2=10y+25=0
y^2-10y-25=0
(y-5)(y-5)=0
y=5
5^x=5
x=1
y^2=10y+25=0
y^2-10y-25=0
(y-5)(y-5)=0
y=5
5^x=5
x=1
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https://hk.answers.yahoo.com/question/index?qid=20090830000051KK01731