Giải thích các bước giải:
h.Ta có:
$7-3x=9-x$
$\to 7-9=3x-x$
$\to -2=2x$
$\to x=-1$
i.Ta có:
$\dfrac{2x+3}{3}=\dfrac{5-4x}{2}$
$\to 2(2x+3)=3(5-4x)$
$\to 4x+6=15-12x$
$\to 16x=9$
$\to x=\dfrac9{16}$
k.Ta có:
$\dfrac{3x-2}{6}-5=\dfrac{3-2(x+7)}{4}$
$\to \dfrac{3x-2}{6}\cdot \:12-5\cdot \:12=\dfrac{3-2\left(x+7\right)}{4}\cdot \:12$
$\to 2\left(3x-2\right)-60=3\left(-2\left(x+7\right)+3\right)$
$\to 6x-64=-6x-33$
$\to 12x=31$
$\to x=\dfrac{31}{12}$
l.Ta có:
$3x+7=8x-12$
$\to 8x-3x=7+12$
$\to 5x=19$
$\to x=\dfrac{19}{5}$
m.Ta có:
$2.3x-2(0.7+2x)=3.6-1.7x$
$\to 2.3x-1.4-4x=3.6-1.7x$
$\to -1.7x-1.4=3.6-1.7x$
$\to 0=5$ vô lý
$\to$Phương trình vô nghiệm
