Tìm x:
\(\frac{3x+2}{5x+7}=\frac{3x-1}{5x+1}\)
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NV
2
7 tháng 10 2016
\(\frac{3x+2}{5x+7}=\frac{5x-1}{5x+1}\)
\(\Leftrightarrow\left(3x+2\right)\left(5x+1\right)=\left(5x-1\right)\left(5x+7\right)\)
\(\Leftrightarrow15x^2+3x+10x+2=25x^2+35x-5x-7\)
\(\Leftrightarrow25x^2+30x-7-15x^2-13x-2=0\)
\(\Leftrightarrow10x^2+17x-9=0\)
.............
HP
2
22 tháng 12 2015
=>(3x+2)(5x+1)=(5x+7)(3x-1)
(3x)(5x+1)+2(5x+1)=(5x)(3x-1)+7(3x-1)
15x2+3x+10x+2=15x2-5x+21x-7
(15x2-15x2)+(3x+10x+5x-21x)=-7-2
0-3x=-9
-3x=-9
x=(-9)/(-3)
x=3
22 tháng 12 2015
\(\frac{3x+2}{5x+7}\)=\(\frac{3x-1}{5x+1}\)
\(\Rightarrow\)\(\frac{3x+2}{3x-1}\)= \(\frac{5x+7}{5x+1}\)\(\Rightarrow\)1+\(\frac{3}{3x-1}\)=1+\(\frac{6}{5x+1}\)
\(\Rightarrow\)\(\frac{3}{3x-1}\)= \(\frac{6}{5x+1}\)\(\Rightarrow\)3.(5x+1) = 6.(3x-1)
\(\Rightarrow\)15x+3 = 18x -6
\(\Rightarrow\)3x = 6 +3
\(\Rightarrow\)x =3
HL
1
27 tháng 11 2015
<=>(3x+2)(5x+1)=(3x-1)(5x+7)
<=>\(15x^2+10x+3x+2=15x^2-5x+21x-7\)
<=>-3x=-9
<=>x=3
tick hộ mình nhá
LP
1
22 tháng 2 2017
a ) \(\frac{3x+2}{5x+7}=\frac{3x-1}{5x+1}\)
\(\Leftrightarrow\left(3x+2\right)\left(5x+1\right)=\left(3x-1\right)\left(5x+7\right)\)
\(\Leftrightarrow3x\left(5x+1\right)+2\left(5x+1\right)=3x\left(5x+7\right)-\left(5x+7\right)\)
\(\Leftrightarrow15x^2+3x+10x+2=15x^2+21x-5x-7\)
\(\Leftrightarrow15x^2+13x+2=15x^2+16x-7\)
\(\Leftrightarrow13x+2=16x-7\)
\(\Leftrightarrow13x-16x=-7-2\)
\(\Leftrightarrow-3x=-9\)
\(\Rightarrow x=3\)
b ) tương tự
LP
0
KN
5 tháng 3 2020
\(\frac{3x-7}{5}=\frac{2x-1}{3}\)
\(\Leftrightarrow9x-21=10x-5\)
\(\Leftrightarrow-x=16\Leftrightarrow x=-16\)
\(\frac{4x-7}{12}-x=\frac{3x}{8}\)
\(\Leftrightarrow\frac{4x-7-12x}{12}=\frac{3x}{8}\)
\(\Leftrightarrow\frac{-7-8x}{12}=\frac{3x}{8}\)
\(\Leftrightarrow-56-64x=36x\)
\(\Leftrightarrow-56=100x\Leftrightarrow x=\frac{-14}{25}\)
KN
5 tháng 3 2020
\(\frac{x-2009}{1234}+\frac{x-2009}{5678}-\frac{x-2009}{197}=0\)
\(\Leftrightarrow\left(x-2019\right)\left(\frac{1}{1234}+\frac{1}{5678}-\frac{1}{197}\right)=0\)
Vì \(\left(\frac{1}{1234}+\frac{1}{5678}-\frac{1}{197}\right)\ne0\)nên x - 2019 = 0
Vậy x = 2019
\(\frac{5x-8}{3}=\frac{1-3x}{2}\)
\(\Leftrightarrow10x-16=3-9x\)
\(\Leftrightarrow19x=19\Leftrightarrow x=1\)
2 tháng 7 2018
a) Ta có: \(\frac{3x+2}{5x+7}=\frac{3x-1}{5x+1}\)
\(\Leftrightarrow\left(3x+2\right)\left(5x+1\right)=\left(5x+7\right)\left(3x-1\right)\)
\(\Leftrightarrow3x\left(5x+1\right)+2\left(5x+1\right)=5x\left(3x-1\right)+7\left(3x-1\right)\)
\(\Leftrightarrow15x^2+3x+10x+2=15x^2-5x+21x-7\)
\(\Leftrightarrow15x^2-15x^2+3x+10x+5x-21x=-7-2\)
\(\Leftrightarrow-3x=-9\)
\(\Leftrightarrow x=3\)
Vậy x = 3
b) Ta có: \(\frac{x+1}{2x+1}=\frac{0,5x+2}{x+3}\Leftrightarrow\left(x+1\right)\left(x+3\right)=\left(2x+1\right)\left(0,5x+2\right)\)
\(\Leftrightarrow x\left(x+3\right)+\left(x+3\right)=2x\left(0,5x+2\right)+\left(0,5x+2\right)\)
\(\Leftrightarrow x^2+3x+x+3=x^2+4x+0,5x+2\)
\(\Leftrightarrow x^2-x^2+3x+x-4x-0,5x=2-3\)
\(\Leftrightarrow-0,5x=-1\Leftrightarrow x=2\)
Vậy x = 2
\(\frac{3x+2}{5x+7}=\frac{3x-1}{5x+1}\)
\(\Rightarrow\left(3x+2\right)\left(5x+1\right)=\left(3x-1\right)\left(5x+7\right)\)
\(\Rightarrow15x^2+10x+3x+2=15x^2-5x+21x-7\)
\(3x=9\)
\(x=3\)
Ta có: (3x+2)(5x+1)=(5x+7)(3x-1) (ĐKXĐ: x khác -7/5, x khác -1/5)
=> 15x2+13x+2=15x2+16x-7
=> 3x-9=0 =>x=3 (chọn)