B1: giải phương trình từ bai 1 đến 2
a, 1,2 – x – 0,8 = -20,9+x
b,2,3x-20,7+2x=3,6-1,7x
c,4x-5 = 2+7
B2:
a,x- 3/5=6- 1-2x/3
b, 3x-2/6 -5= 3-2x+7/4
c,2(x+ 3/5)= 5- (13/5+x)
d,10x-12-3x=6+x
e,7x-1/6 +2x=16-x/5
f,3x-1/4 + 6x-2/8 = 1-3x/6
g,5x-4/3=2+3x/2
mấy cái nào mình cách ra là nó là 1 cái riêng con viết dính vao thì là phần của nó
ai làm xong cả 2 bài vote 5 star
B1: giải phương trình từ bai 1 đến 2 a, 1,2 – x – 0,8 = -20,9+x b,2,3x-20,7+2x=3,6-1,7x c,4x-5 = 2+7 B2: a,x- 3/5=6- 1-2x/3 b, 3x-2/6 -5= 3-2x+7/4
By Jade
Đáp án:
$\begin{array}{l}
B1)\\
a)1,2 – x – 0,8 = – 20,9 + x\\
\Rightarrow x + x = 1,2 – 0,8 + 20,9\\
\Rightarrow 2x = 0,4 + 20,9\\
\Rightarrow 2x = 21,3\\
\Rightarrow x = 10,65\\
b)2,3x + 20,7 + 2x = 3,6 – 1,7x\\
\Rightarrow 2,3x + 2x + 1,7x = 3,6 – 20,7\\
\Rightarrow 6x = – 17,1\\
\Rightarrow x = – 17,1:6 = – \dfrac{{57}}{{20}}\\
c)4x – 5 = 2 + 7\\
\Rightarrow 4x = 9 + 5\\
\Rightarrow 4x = 14\\
\Rightarrow x = \dfrac{7}{2}\\
B2)a)x – \dfrac{3}{5} = 6 – \dfrac{{1 – 2x}}{3}\\
\Rightarrow x – \dfrac{3}{5} = 6 – \dfrac{1}{3} + \dfrac{2}{3}x\\
\Rightarrow x – \dfrac{2}{3}x = 6 – \dfrac{1}{3} + \dfrac{3}{5}\\
\Rightarrow \dfrac{1}{3}x = \dfrac{{94}}{{15}}\\
\Rightarrow x = \dfrac{{94}}{5}\\
b)\dfrac{{3x – 2}}{6} – 5 = 3 – \dfrac{{2x + 7}}{4}\\
\Rightarrow \dfrac{x}{2} – \dfrac{1}{3} – 5 – 3 + \dfrac{x}{2} + \dfrac{7}{4} = 0\\
\Rightarrow x – \dfrac{{79}}{{12}} = 0\\
\Rightarrow x = \dfrac{{79}}{{12}}\\
c)2\left( {x + \dfrac{3}{5}} \right) = 5 – \left( {\dfrac{{13}}{5} + x} \right)\\
\Rightarrow 2x + \dfrac{6}{5} = 5 – \dfrac{{13}}{5} – x\\
\Rightarrow 2x + x = 5 – \dfrac{{13}}{5} – \dfrac{6}{5}\\
\Rightarrow 3x = \dfrac{6}{5}\\
\Rightarrow x = \dfrac{2}{5}\\
d)10x – 12 – 3x = 6 + x\\
\Rightarrow 10x – 3x – x = 6 + 12\\
\Rightarrow 6x = 18\\
\Rightarrow x = 3\\
e)\dfrac{{7x – 1}}{6} + 2x = \dfrac{{16 – x}}{5}\\
\Rightarrow \dfrac{{7x}}{6} – \dfrac{1}{6} + 2x = \dfrac{{16}}{5} – \dfrac{x}{5}\\
\Rightarrow \left( {\dfrac{{7x}}{6} + 2x + \dfrac{x}{5}} \right) = \dfrac{{16}}{5} + \dfrac{1}{6}\\
\Rightarrow \dfrac{{101}}{{30}}x = \dfrac{{101}}{{30}}\\
\Rightarrow x = 1\\
f)\dfrac{{3x – 1}}{4} + \dfrac{{6x – 2}}{8} = \dfrac{{1 – 3x}}{6}\\
\Rightarrow \dfrac{{3x – 1}}{4} + \dfrac{{3x – 1}}{4} = \dfrac{{1 – 3x}}{6}\\
\Rightarrow \dfrac{{3x – 1}}{2} = \dfrac{{1 – 3x}}{6}\\
\Rightarrow 3\left( {3x – 1} \right) = 1 – 3x\\
\Rightarrow 9x – 3 = 1 – 3x\\
\Rightarrow 9x + 3x = 1 + 3\\
\Rightarrow 12x = 4\\
\Rightarrow x = \dfrac{1}{3}\\
g)\dfrac{{5x – 4}}{3} = \dfrac{{2 + 3x}}{2}\\
\Rightarrow 2\left( {5x – 4} \right) = 3\left( {2 + 3x} \right)\\
\Rightarrow 10x – 8 = 6 + 9x
\end{array}$
$ \Rightarrow x = 14$
Vậy x=14