Question

25.5 mủ x+5 = 5mủ 8

124+225:(x-3) mủ 2=57

Answer 1

Giải:

a) \(25.5^{x+5}=5^8\)

\(\Leftrightarrow5^2.5^{x+5}=5^8\)

\(\Leftrightarrow5^{x+7}=5^8\)

\(\Leftrightarrow x+7=8\)

\(\Leftrightarrow x=1\)

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b) \(124+\dfrac{225}{\left(x-3\right)^2}=57\)

\(\Leftrightarrow\dfrac{15^2}{\left(x-3\right)^2}=-67\)

\(\Leftrightarrow\left(\dfrac{15}{x-3}\right)^2=-67\)

Mà \(\left(\dfrac{15}{x-3}\right)^2\ge0,\forall x\left(x\ne3\right)\)

Suy ra không có x thỏa mãn

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