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a) Ta có: \(\dfrac{21}{25}\cdot\dfrac{11}{9}\cdot\dfrac{5}{7}\)
\(=\dfrac{21\cdot11\cdot5}{25\cdot9\cdot7}\)
\(=\dfrac{3\cdot7\cdot11\cdot5}{5\cdot5\cdot3\cdot3\cdot7}\)
\(=\dfrac{11}{5\cdot3}=\dfrac{11}{15}\)
x+126/216=204/216-24/216
=>x+126/216=108/216
=>x=108/216-126/216
=>x=-18/216
=>x=-1/12
a, x + 7/12 = 17/18 - 1/9
x + 7/12 = 15/18
x = 15/18 - 7/12
x = 1/4
b, 29/30 - ( 13/23 + x ) = 7/69
( 13/23 + x ) = 29/30 - 7/69
13/23 + x = 199/230
x = 199/230 - 13/23
x = 3/10
hok tốt
\(\text{a)}25\%-\frac{3}{2}+0,5.\frac{12}{5}\)
\(=\frac{1}{4}-\frac{3}{2}+\frac{1}{2}.\frac{12}{5}\)
\(=-\frac{5}{8}+\frac{6}{5}\)
\(=-\frac{25}{40}+\frac{48}{40}\)
\(=\frac{23}{40}\)
\(b)0,25.\frac{7}{3}.30.\text{ }0,5.\frac{8}{45}\)
\(=\frac{1}{4}.\frac{7}{3}.30.\frac{1}{2}.\frac{8}{45}\)
\(=\frac{7}{12}.(30.\frac{8}{90})\)
\(=\frac{7}{12}.\frac{8}{3}\)
\(=\frac{14}{9}\)
\(c)\frac{9}{23}.\frac{5}{8}+\frac{9}{23}.\frac{3}{8}-\frac{9}{23}\)
\(=\frac{9}{23}.\left(\frac{5}{8}+\frac{3}{8}-1\right)\)
\(=\frac{9}{23}.0\)
\(=0\)
Tìm x :
a) x + 7/12 = 17/18 - 1/9
x + 7/12 = 15/18
x = 15/18 - 7/12
x = 31/36
mik nè
a ) x + 7/12 = 17/18 - 1/9
x + 7/12 = 17/18 - 2/18
x + 7/12 = 5/18
x = 5/18 - 7/12
x = 10/36 - 21/36
x = -11/36
b ) 29/30 - ( 13/23 + x ) = 7/69
29/30 - 13/23 - x = 7/69
29/30 - 39/69 - x = 7/69
29/30 - x = 7/69 + 39/69
29/30 - x = 46/69
x = 29/30 - 46/69
x = 3/10
c ) x + 1/4 - 1/3 = 7/46
x + 3/12 - 4/12 = 7/46
x + -1/12 = 7/46
x = 7/46 + 1/12
x = 65/276
Tk mình nha !!! Chúc học giỏi !!!
Ai thấy đúng TK mình nhé !!!!
\(23-|x+9|=30\)
\(|x+9|=23-30\)
\(x+9=-7\)
\(x=\left(-7\right)-9\)
\(x=-16\)
Vậy x = -16
23 - | x + 9 | = 30
| x + 9 | = 23 - 30
| x + 9 | = -7
\(\Rightarrow\orbr{\begin{cases}x+9=7\\x+9=-7\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=7-9\\x=-7-9\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=-2\\x=-16\end{cases}}\)
Vậy: ....