Câu hỏi của Chien Hong Pham

Question

Tìm x biết

a)/x-30/-15=0

b) /20-x/-5=10

c) /20-x/+6=0

d) /x-50/=0

e) /x-10//30=3

giúp mink nhé mai mink nộp bài rồi

Ngọc Nguyễn Minh · Accepted Answer

a) $\left|x-30\right|-15=0$

$\Rightarrow\left|x-30\right|=15$

$\Rightarrow\left[\begin{array}{nghiempt}x-30=15\x-30=-15\end{array}\right.$ $\Rightarrow\left[\begin{array}{nghiempt}x=45\x=15\end{array}\right.$

Câu trả lời:

a) $\left|x-30\right|-15=0$

$\Rightarrow\left|x-30\right|=15$

$\Rightarrow\left[\begin{array}{nghiempt}x-30=15\x-30=-15\end{array}\right.$ $\Rightarrow\left[\begin{array}{nghiempt}x=45\x=15\end{array}\right.$

Trần Nguyễn Bảo Quyên · Answer

$a.$

$\left|x-30\right|-15=0$

$\Rightarrow\left|x-30\right|=0+15=15$

$\Rightarrow\left[\begin{array}{nghiempt}x-30=15\x-30=-15\end{array}\right.$

$\Rightarrow\left[\begin{array}{nghiempt}x=15+30=45\x=-15+30=15\end{array}\right.$

Vậy $\left[\begin{array}{nghiempt}x=45\x=15\end{array}\right.$

$b.$

$\left|20-x\right|-5=10$

$\Rightarrow\left|20-x\right|=10+5=15$

$\Rightarrow\left[\begin{array}{nghiempt}20-x=15\20-x=-15\end{array}\right.$

$\Rightarrow\left[\begin{array}{nghiempt}x=20-15=5\x=-20-15=-35\end{array}\right.$

Vậy $\left[\begin{array}{nghiempt}x=5\x=-35\end{array}\right.$

$c.$

$\left|20-x\right|+6=0$

$\Rightarrow\left|20-x\right|=0-6=-6$

$\Rightarrow x\in\varnothing$

$d.$

$\left|x-50\right|=0$

$\Rightarrow x-50=0$

$\Rightarrow x=0+50=50$

Vậy $x=50$

$e.$

$\frac{\left|x-10\right|}{30}=3$

$\Rightarrow\left|x-10\right|=3.30=90$

$\Rightarrow\left[\begin{array}{nghiempt}x-10=90\x-10=-90\end{array}\right.$

$\Rightarrow\left[\begin{array}{nghiempt}x=90+10=100\x=-90+10=-80\end{array}\right.$

Vậy $\left[\begin{array}{nghiempt}x=100\x=-80\end{array}\right.$