Toán Lớp 9: Tìm x
A, √25x-25 – 15/2√x-1/9= 6 + √x-1
B,√x^2-4x-4=x-2
Giúp vz ạ
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Toán Lớp 9: Tìm x
A, √25x-25 – 15/2√x-1/9= 6 + √x-1
B,√x^2-4x-4=x-2
Giúp vz ạ
Comments ( 1 )
a)Dkxd:x \ge 1\\
\sqrt {25x – 25} – \dfrac{{15}}{2}\sqrt {\dfrac{{x – 1}}{9}} = 6 + \sqrt {x – 1} \\
\Leftrightarrow 5.\sqrt {x – 1} – \dfrac{{15}}{2}.\dfrac{{\sqrt {x – 1} }}{3} – \sqrt {x – 1} = 6\\
\Leftrightarrow 5\sqrt {x – 1} – \dfrac{5}{2}\sqrt {x – 1} – \sqrt {x – 1} = 6\\
\Leftrightarrow \dfrac{3}{2}\sqrt {x – 1} = 6\\
\Leftrightarrow \sqrt {x – 1} = 4\\
\Leftrightarrow x – 1 = 16\\
\Leftrightarrow x = 17\left( {tmdk} \right)\\
Vậy\,x = 17\\
b)Dkxd:x \ge 2\\
\sqrt {{x^2} – 4x – 4} = x – 2\\
\Leftrightarrow {x^2} – 4x – 4 = {x^2} – 4x + 4\\
\Leftrightarrow – 4 = 4\left( {ktm} \right)
\end{array}$