13/07/2010

09/10/2011

a. = 2xy + 2x² - 4xy² - 2

b. 2 + \(\sqrt{2x-1}=x\)       ĐKXĐ: \(x\ge0,5\)

<=> \(\sqrt{2x-1}\) = x - 2

<=> 2x - 1 = (x - 2)²

<=> 2x - 1 = x² - 4x + 4

<=> -x² + 2x + 4x - 4 - 1 = 0

<=> -x² + 6x - 5 = 0

<=> -x² + 5x + x - 5 = 0

<=> -(-x² + 5x + x - 5) = 0

<=> x² - 5x - x + 5 = 0

<=> x(x - 5) - (x - 5) = 0

<=> (x - 1)(x - 5) = 0

<=> \(\left[{}\begin{matrix}x-1=0\\x-5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=5\end{matrix}\right.\)

???

:)

bẻ lái cực gắt

good teacher

a. \(\sqrt{8^2+6^2}\) = \(\sqrt{64+36}\) = \(\sqrt{100}\) = 10

b. \(\sqrt{\left(0,3\right)^2}\)= 0,3

c. \(\sqrt{\left(-0,3\right)^2}\) = 0,3

d. -0,2\(\sqrt{\left(-0,5\right)^2}\) = -0,2 . 0,5 = -0,1

x \(\ge\) 0