Question

[Nguyễn Phạm Thanh Huyền]

Giúp mk: Tìm x

a,-(12)(x-5)+7(3-x)=5

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

Thế nhé, mk cần gấp. Ai nhah mk tick cho🙂

Answer 1

[Phùng Minh Quân]

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

\(\Leftrightarrow\)\(\left(-12\right)x+60+21-7x=5\)

\(\Leftrightarrow\)\(\left(-12\right)x-7x=5-60-21\)

\(\Leftrightarrow\)\(x\left(-12-7\right)=-76\)

\(\Leftrightarrow\)\(x.\left(-19\right)=-76\)

\(\Leftrightarrow\)\(x=\frac{-76}{-19}\)

\(\Leftrightarrow\)\(x=4\)

Vậy \(x=4\)

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

\(\Leftrightarrow\)\(\orbr{\begin{cases}x-2=0\\x+4=0\end{cases}}\)

\(\Leftrightarrow\)\(\orbr{\begin{cases}x=2\\x=-4\end{cases}}\)

Vậy \(x\in\left\{2;-4\right\}\)