Question

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a) \(|1-2x|\)=3

b) ( x + 1 ).( 1 - 5x )=0

c) 1+ 2+ 3 +...+ x =5050 (xEN)

Bạn nào thông minh giải hộ mình nhá

Answer 1

\(a;\left|1-2x\right|=3\)

\(\Leftrightarrow\left|2x-1\right|=3\Leftrightarrow2x-1=\pm3\)

\(\Leftrightarrow\orbr{\begin{cases}2x-1=3\\2x-1=-3\end{cases}\Leftrightarrow\orbr{\begin{cases}2x=4\\2x=-2\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=4:2=2\\x=\left(-2\right):2=-1\end{cases}}}\)

   Vậy x=2;-1

Answer 2

\(b;\left(x+1\right)\left(1-5x\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x+1=0\\1-5x=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-1\\5x=1\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=-1\\x=\frac{1}{5}\end{cases}}}\)

Answer 3

\(c;1+2+3+...+x=5050\)

\(\Leftrightarrow\frac{\left(x+1\right)x}{2}=5050\)

\(\Leftrightarrow\left(x+1\right)x=10100\)

\(\Leftrightarrow\left(x+1\right)x=100\times101\)

\(\Rightarrow x=100\)