3x :9-21=67
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\(=\left(25+\dfrac{12}{67}+9+\dfrac{13}{41}-8-\dfrac{12}{67}+3+\dfrac{28}{41}\right)\cdot\dfrac{-21}{13}\)
\(=\left(25+9-8+3+1\right)\cdot\dfrac{-21}{13}=\dfrac{-630}{13}\)
\(a,\Rightarrow12x-91=101\\ \Rightarrow12x=192\\ \Rightarrow x=16\\ b,\Rightarrow x:23+45=133\\ \Rightarrow x:23=88\\ \Rightarrow x=\dfrac{88}{23}\\ c,\Rightarrow\left(6x-39\right):7=3\\ \Rightarrow6x-39=21\\ \Rightarrow6x=60\\ \Rightarrow x=10\\ d,\Rightarrow3x-24=\dfrac{148}{73}\\ \Rightarrow3x=\dfrac{1900}{73}\\ \Rightarrow x=\dfrac{1900}{219}\\ e,\Rightarrow\left[{}\begin{matrix}x=0\\x=10\end{matrix}\right.\\ f,\Rightarrow\left[{}\begin{matrix}x=-1\\x=2\end{matrix}\right.\\ d,\left(9-x\right)^3=64=4^3\\ \Rightarrow9-x=4\\ \Rightarrow x=5\\ h,\Rightarrow x=27\\ i,\Rightarrow6x=312\cdot12=624\cdot6\\ \Rightarrow x=624\\ j,\Rightarrow\left(19x+104\right):14=25-42=-17\\ \Rightarrow19x+104=-238\\ \Rightarrow19x=-342\\ \Rightarrow x=-18\)
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`67.21 + 33.22`
`= 67.7.3 + 3.11.22`
`= 3.(67.7 + 22.11)`
`= 3.(469 + 242)`
`= 3. 711`
`= 2133`
67.21+33.22
=(66+1).21+33.(21+1)
=66.21+21+33.21+33
=2.33.21+33.21+21+33
=3.33.21+54
=3.3.11.21+54
=9.(10+1).21+54
=(90+9).21+54
=(100-1).21+54
=2100-21+54
=2133
a) Đề:
<=> (2x - 17). 56 = 59
<=> 2x - 17 = 59 : 56
<=> 2x - 17 = 53
<=> 2x - 17 = 125
<=> 2x = 142
<=> x = 71
Vậy x = 71
b) Đề:...........
<=> 3. x3 - 67 = 125
<=> 3. x3 = 192
<=> x3 = 64
<=> x = 4
Vậy x = 4
c) Đề:...........
<=> 53x - 2 - 2. 125 = 125. 3
<=> 53x - 2 - 250 = 375
<=> 53x - 2 = 625
<=> 53x - 2 = 54
<=> 3x - 2 = 4
<=> 3x = 6
<=> x = 2
Vậy x = 2
a, \(\left|9+x\right|=2x\)
\(\Leftrightarrow\orbr{\begin{cases}9+x=2x\\9+x=-2x\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}9=2x-x\\9=-2x-x\end{cases}\Leftrightarrow\orbr{\begin{cases}9=x\\9=-3x\end{cases}}}\)
\(\Rightarrow\orbr{\begin{cases}x=9\\x=-3\end{cases}}\)
b, \(\left|5x\right|-3x=2\)
\(\Leftrightarrow\orbr{\begin{cases}5x-3x=2\\5x-3x=-2\end{cases}}\Leftrightarrow\orbr{\begin{cases}2x=2\\2x=-2\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=1\\x=-1\end{cases}}\)