Đáp án: a.$x=\dfrac{-9}{7}$
b.$x=\dfrac{-2}{45}$
c.$x=\dfrac34$
d.$x=-\dfrac3{26}$
Giải thích các bước giải:
a.Ta có:
$\dfrac34:x=\dfrac{-7}{12}$
$\to x=\dfrac34:\dfrac{-7}{12}$
$\to x=\dfrac34\cdot \dfrac{12}{-7}$
$\to x=\dfrac{-9}{7}$
b.Ta có:
$\dfrac34\cdot x+\dfrac15=\dfrac16$
$\to \dfrac34\cdot x=\dfrac16-\dfrac15$
$\to \dfrac34\cdot x=\dfrac{-1}{30}$
$\to x=\dfrac{-1}{30}:\dfrac34$
$\to x=\dfrac{-1}{30}\cdot \dfrac43$
$\to x=\dfrac{-2}{45}$
c.Ta có:
$\dfrac38-\dfrac16\cdot x=\dfrac14$
$\to \dfrac16\cdot x=\dfrac38-\dfrac14$
$\to \dfrac16\cdot x=\dfrac18$
$\to x=\dfrac18:\dfrac16$
$\to x=\dfrac18\cdot 6$
$\to x=\dfrac34$
d.Ta có:
$\dfrac13+\dfrac12:x=-4$
$\to \dfrac12:x=-4-\dfrac13$
$\to \dfrac12:x=\dfrac{-13}3$
$\to x=\dfrac12:\dfrac{-13}3$
$\to x=\dfrac12\cdot\dfrac3{-13}$
$\to x=-\dfrac3{26}$
