Question

Tính nhanh

a, −57(75−36)−75(36−57)

b, 19−42(−19)+38.5

Tìm x

a,7x(x-10)=0

b, (4-x) . ( 2x+6)=0

c, -12(x-5) + 7 . ( 3-x ) =5

Answer 1

Bài 2: Tìm x

a, \(7x\left(x-10\right)=0\)

\(\Rightarrow x\left(x-10\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=0\\x-10=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=10\end{matrix}\right.\)

b, \(\left(4-x\right)\left(2x+6\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}4-x=0\\2x+6=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=4\\x=-3\end{matrix}\right.\)

c, \(-12\left(x-5\right)+7\left(3-x\right)=5\)

\(\Rightarrow-12x+60+21-7x=5\)

\(\Rightarrow-19x=5-60-21\)

\(\Rightarrow-19x=-76\Rightarrow x=4\)

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