Đáp án + Giải thích các bước giải:
$\text{a) $\dfrac{3}{4x}$ - $\dfrac{10x + 7y}{12xy}$ + $\dfrac{5}{6y}$ }$
$\text{= $\dfrac{3 .3y}{4x . 3y}$ - $\dfrac{10x + 7y}{12xy}$ + $\dfrac{5 . 2x}{6y . 2x}$ }$
$\text{= $\dfrac{9y}{12y}$ - $\dfrac{10x + 7y}{12xy}$ + $\dfrac{10x}{12y}$ }$
$\text{= $\dfrac{9y - (10x + 7y) + 10x}{12xy}$ }$
$\text{= $\dfrac{9y - 10x - 7y + 10x}{12xy}$ }$
$\text{= $\dfrac{2y}{12xy}$ }$
$\text{b) $\dfrac{1}{2a}$ - $\dfrac{x^{2} - 2ax}{2ax^{2}}$ - $\dfrac{2}{x}$ }$
$\text{= $\dfrac{1 . x^{2} }{2a . x^{2}}$ - $\dfrac{x^{2} - 2ax}{2ax^{2}}$ - $\dfrac{2 . 2ax}{2ax^{2}}$}$
$\text{= $\dfrac{x^{2} }{2ax^{2}}$ - $\dfrac{x^{2} - 2ax}{2ax^{2}}$ - $\dfrac{4ax}{2ax^{2}}$}$
$\text{= $\dfrac{x^{2} - (x^{2} - 2ax) - 4ax}{2ax^{2}}$ }$
$\text{= $\dfrac{x^{2} - x^{2} + 2ax - 4ax}{2ax^{2}}$ }$
$\text{= $\dfrac{-2ax}{2ax^{2}}$ }$
$\text{= $\dfrac{-1}{x}$ }$
$\text{= $\dfrac{1}{6x}$ }$
Cho mình xin câu tl hay nhất nha!
