Quadratic Equations

👨🏻‍🏫 學術台數學

你知

2011-10-05 5:58 am

Solve the following equations for x:
9x - 3√x - 2 = 0

回答 (2)

用戶25975

2011-10-05 6:05 am

✔ 最佳答案

Sub y = √x, then the equation becomes:

9y2 - 3y - 2 = 0

(3y + 1)(3y - 2) = 0

y = -1/3 (rej.) or 2/3

√x = 2/3

x = 4/9

參考: 原創答案

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徐偉國

2011-10-05 6:12 am

9x-3square root x-2=0
9x-2=3 square root x
(9x-2)^2=(3 square root x)^2
81x^2-36x+4=9x
81x^2-45x+4=0
(9x-1)(9x-4)=0
x= 4/9 or 1/9(rej.)
x=4/9

參考: me

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