Question

a,|2x|.|3.5|=|-2.8| b,|x-1/2|+|x+y|=0

Answer 1

Answer 2

a) \(|2x|.|3.5|=|-2.8|\)

\(\Rightarrow|2x|.|15|=|-16|\)

\(\Rightarrow|2x|.15=16\)

\(\Rightarrow|2x|=\dfrac{16}{15}\)

Ta có hai trường hợp:

1) \(2x\ge0\)

\(\Rightarrow|2x|=2x=\dfrac{16}{15}\Rightarrow x=\dfrac{8}{15}\)

2) \(2x< 0\)

\(\Rightarrow|2x|=-2x=\dfrac{16}{15}\Rightarrow-x=\dfrac{8}{15}\Rightarrow x=-\dfrac{8}{15}\)

Vậy \(x=\dfrac{8}{15}\) hoặc \(x=-\dfrac{8}{15}\).

b) \(|x-\dfrac{1}{2}|+|x+y|=0\)

\(\Rightarrow\left\{{}\begin{matrix}x-\dfrac{1}{2}=0\\x+y=0\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{1}{2}\\y=-\dfrac{1}{2}\end{matrix}\right.\)

Vậy \(\left\{{}\begin{matrix}x=\dfrac{1}{2}\\y=-\dfrac{1}{2}\end{matrix}\right.\)