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a. \(\dfrac{8}{7}-\dfrac{1}{7}:\left(\dfrac{x}{3}-2\right)=-1\)
\(-\dfrac{1}{7}:\left(\dfrac{x}{3}-2\right)=\dfrac{15}{7}\)
\(\dfrac{x}{3}-2=\dfrac{-1}{15}\)
\(\dfrac{x}{3}=\dfrac{29}{15}\)
\(x=5,8\)
b. \(\dfrac{5}{8}+\dfrac{1}{4}\left(2x-1\right)=\dfrac{5}{4}\)
\(\dfrac{1}{4}\left(2x-1\right)=\dfrac{5}{8}\)
\(2x-1=\dfrac{5}{2}\)
\(2x=\dfrac{7}{2}\)
\(x=\dfrac{7}{4}\)
\(a,3.\left(2x+8\right)-\left(5x+2\right)=0\)
\(\Rightarrow6x+24-5x+2=0\)
\(\Rightarrow6x-5x=0-24-2\)
\(\Rightarrow x=-26\)
\(5.\left(7-3x\right)+7.\left(2+2x\right)=0\)
\(\Rightarrow35-15x+14+14x=0\)
\(\Rightarrow-15x+14x=0-35-14\)
\(\Rightarrow-x=-49\)
\(\Rightarrow x=49\)
Tìm x
a, 3.(2x + 8) - (5x + 2)=0 ............. Hok Tốt nhé ..............
\(\Leftrightarrow3x+24-5x-2=0\) ........ Nhớ k cho mik nhé .........
\(\Leftrightarrow x+22=0\)
\(\Rightarrow x=-22\)
b, 5.(7 - 3x) + 7.( 2 + 2x)
\(\Leftrightarrow35-15x+14+14x\)
\(\Leftrightarrow-15x+14x=0-35-14\)
\(\Leftrightarrow-x=-49\)
\(\Rightarrow x=49\)
Bài 1L
a) \(\left(x-7\right)\left(x+3\right)< 0\)
TH1:
\(\hept{\begin{cases}x-7>0\\x+3< 0\end{cases}\Leftrightarrow\hept{\begin{cases}x>7\\x< -3\end{cases}}}\)( loại )
TH2:
\(\hept{\begin{cases}x-7< 0\\x+3>0\end{cases}\Leftrightarrow\hept{\begin{cases}x< 7\\x>-3\end{cases}\Leftrightarrow}-3< x< 7}\)( chọn )
Vậy \(-3< x< 7\)
Bài 2:
a) \(\left(5x+8\right)-\left(2x-15\right)+21=2x-5\)
\(\Leftrightarrow5x+8-2x+15+21=2x-5\)
\(\Leftrightarrow5x-2x-2x=-5-21-8-15\)
\(\Leftrightarrow x=-49\)
Vậy ...
a) \(\left(x-1\right)^3=8=2^3\)
\(x-1=2\)
\(x=2+1=3\)
b) \(7^{2x-6}=49=7^2\)
\(2x-6=2\)
\(2x=6+2=8\)
\(x=8:2=4\)
c) \(\left(2x-14\right)^7=128=2^7\)
\(2x-14=2\)
\(2x=14+2=16\)
\(x=16:2=8\)
d) \(x^4\cdot x^5=5^3\cdot5^6=5^4\cdot5^5\)
\(x=5\)
e) \(3\cdot\left(x+2\right):7\cdot4=120\)
\(x+2=120:3\cdot7:4\)
\(x+2=70\)
\(x=70-2=68\)
Lời giải:
a. $(x-1)^3=8=2^3$
$\Rightarrow x-1=2$
$\Rightarrow x=3$
b. $7^{2x-6}=49=7^2$
$\Rightarrow 2x-6=2$
$\Rightarrow 2x=8$
$\Rightarrow x=4$
c. $(2x-14)^7=128=2^7$
$\Rightarrow 2x-14=2$
$\Rightarrow 2x=16$
$\Rightarrow x=18$
d.
$x^4.x^5=5^3.5^6$
$x^9=5^9$
$\Rightarrow x=5$
e.
$3(x+2):7=120:4=30$
$3(x+2)=30.7=210$
$x+2=210:3=70$
$x=70-2=68$
a, \(\frac{5}{9}+\left(\frac{3}{2}-2x\right)=-\frac{4}{7}\)
\(\Leftrightarrow\frac{3}{2}-2x=-\frac{4}{7}-\frac{5}{9}\)
\(\Leftrightarrow\frac{3}{2}-2x=\frac{-36}{63}-\frac{35}{63}\)
\(\Leftrightarrow\frac{3}{2}-2x=-\frac{71}{63}\)
\(\Leftrightarrow2x=\frac{3}{2}+\frac{71}{63}\)
\(\Leftrightarrow2x=\frac{189}{126}+\frac{142}{126}\)
\(\Leftrightarrow2x=\frac{331}{126}\)
\(\Leftrightarrow x=\frac{331}{126}:2\)
\(\Leftrightarrow x=\frac{331}{126}.\frac{1}{2}\)
\(\Leftrightarrow x=\frac{331}{252}\)
Vậy \(x=\frac{331}{252}\)
a)2x=8:2
2x=4
x=2
b)x-5+7=2
x-5=5
x=10
a)\(2x.2=8\)
\(2x=8:2\)
\(2x=4\)
\(x=4:2\)
\(x=2\)
b,\(x-5+7=2\)
\(x+2=2\)
\(x=2-2\)
\(x=0\)