Tìm x ∈ Z: a) 2+x/3-x = 1/9 b) 11-x/3+x = 9/144 24/10/2021 Bởi Katherine Tìm x ∈ Z: a) 2+x/3-x = 1/9 b) 11-x/3+x = 9/144
$\begin{array}{l} a)\,\,\dfrac{2+x}{3-x} = \dfrac19 \\\Leftrightarrow 9(2+x)=3-x \\\Leftrightarrow 18+9x=3-x \\\Leftrightarrow 9x+x=3-18 \\\Leftrightarrow 10x=-15\\\Leftrightarrow x=-\dfrac23 \\\text{mà}\,\,x \in \mathbb{Z} \\\to x \in \varnothing \\\,\\b)\,\,\dfrac{11-x}{3+x}=\dfrac9{144} \\\Leftrightarrow 144(11-x)=9(3+x) \\\Leftrightarrow 1584-144x=27+9x \\\Leftrightarrow -144x-9x=27-1584 \\\Leftrightarrow -153x=-1557 \\\Leftrightarrow x=\dfrac{173}{17} \\\text{mà}\,\,x \in \mathbb{Z} \\\to x \in \varnothing \end{array}$ Bình luận
Đáp án: ↓↓↓ Giải thích các bước giải: a) `(2+x)/(3-x)` `=` `1/9` ⇔ `9(2+x) = 3 – x` ⇔ `18+9x = 3 – x` ⇔ `9x+x = 3-18` ⇔ `10x = -15` ⇔ `x =` `(-3)/2` b) `(11-x)/(3+x)` `=` `9/144` ⇔ `144(11-x) = 9(3+x)` ⇔ `1584 – 144x = 27 + 9x` ⇔ `-144x – 9x = 27 – 1584` ⇔ ` -153x = -1557` ⇔ ` x =` `73/10` Bình luận
$\begin{array}{l} a)\,\,\dfrac{2+x}{3-x} = \dfrac19 \\\Leftrightarrow 9(2+x)=3-x \\\Leftrightarrow 18+9x=3-x \\\Leftrightarrow 9x+x=3-18 \\\Leftrightarrow 10x=-15\\\Leftrightarrow x=-\dfrac23 \\\text{mà}\,\,x \in \mathbb{Z} \\\to x \in \varnothing \\\,\\b)\,\,\dfrac{11-x}{3+x}=\dfrac9{144} \\\Leftrightarrow 144(11-x)=9(3+x) \\\Leftrightarrow 1584-144x=27+9x \\\Leftrightarrow -144x-9x=27-1584 \\\Leftrightarrow -153x=-1557 \\\Leftrightarrow x=\dfrac{173}{17} \\\text{mà}\,\,x \in \mathbb{Z} \\\to x \in \varnothing \end{array}$
Đáp án:
↓↓↓
Giải thích các bước giải:
a) `(2+x)/(3-x)` `=` `1/9`
⇔ `9(2+x) = 3 – x`
⇔ `18+9x = 3 – x`
⇔ `9x+x = 3-18`
⇔ `10x = -15`
⇔ `x =` `(-3)/2`
b) `(11-x)/(3+x)` `=` `9/144`
⇔ `144(11-x) = 9(3+x)`
⇔ `1584 – 144x = 27 + 9x`
⇔ `-144x – 9x = 27 – 1584`
⇔ ` -153x = -1557`
⇔ ` x =` `73/10`