Question

tìm x thuộc Z biết :

a, | x + 8 | = 6

b, | x - a | = a      (a thuộc Z)

c, 461 + ( x - 45 ) = 387 

d, x ( x+3) = 0 

Answer 1

\(a,|x+8|=6\)

\(\Leftrightarrow\orbr{\begin{cases}x+8=6\\x+8=-6\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=6-8\\x=-6-8\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=-2\\x=-14\end{cases}}\)

\(b;|x-a|=a\)

\(\Leftrightarrow x=a+a\)

\(\Leftrightarrow x=a.2\)

\(c,461+\left(x-45\right)=387\)

\(\Leftrightarrow x-45=74\)

\(\Leftrightarrow x=74+45\)

\(\Leftrightarrow x=119\)

Answer 2

a)\(|x+8|=\mp6\)

\(\orbr{\begin{cases}x+8=6\Rightarrow x=-2\\x+8=-6\Rightarrow x=-14\end{cases}}\)

b)\(\orbr{\begin{cases}x-a=a\Rightarrow a+a=2a\\x-a=-a\Rightarrow-a+a=0\end{cases}}\)

c)\(x-45=387-461\)

\(x-45=-74\)

\(x=-74+45\)

\(x=-29\)

d)\(2x+3x=0\)

\(x\cdot\left(2+3\right)=0\)

\(x\cdot5=0\)

\(x=0\)

nhớ k cho mình nha