Giải thích các bước giải:
b.Ta có:
$-7+14x=0$
$\to 14x=7$
$\to x=\dfrac12$
$\to S=\{\dfrac12\}$
c.Ta có:
$5-3x=6x+7$
$\to 6x+3x=5-7$
$\to 9x=-2$
$\to x=-\dfrac29$
$\to S=\{-\dfrac29\}$
d.Ta có:
$15-8x=9-5x$
$\to 8x-5x=15-9$
$\to 3x=6$
$\to x=2$
$\to S=\{2\}$
e.Ta có:
$2(x+1)=2(x-1)+4$
$\to 2x+2=2x-2+4$
$\to 2x-2x=-2-2+4$
$\to 0=0$ luôn đúng
$\to$Phương trình có vô số nghiệm
$\to S=R$
a.Ta có:
$\dfrac{3-x}{4}-\dfrac{2x+3}{8}=-1$
$\to 2\left(-x+3\right)-\left(2x+3\right)=-8$
$\to -2x+6-2x-3=-8$
$\to -4x+3=-8$
$\to 4x=11$
$\to x=\dfrac{11}{4}$
$\to S=\{\dfrac{11}{4}\}$
b.Ta có:
$x-\dfrac{2x+5}{3}=\dfrac{2x}{3}-2x+1$
$\to x\cdot \:3-\dfrac{2x+5}{3}\cdot \:3=\dfrac{2x}{3}\cdot \:3-2x\cdot \:3+1\cdot \:3$
$\to 3x-\left(2x+5\right)=2x-6x+3$
$\to 3x-2x-5=-4x+3$
$\to x-5=-4x+3$
$\to x+4x=5+3$
$\to 5x=8$
$\to x=\dfrac85$
$\to S=\{\dfrac85\}$
