\(\dfrac{7}{9}\times\dfrac{3}{5}\)
C=\(\dfrac{7}{19}\times\dfrac{5}{8}\times\dfrac{-19}{7}\)
D=\(\dfrac{3}{7}\times\dfrac{9}{11}+\dfrac{3}{7}\times\dfrac{2}{11}\)
C)
`7/19xx5/8xx (-19)/7`
`=7/19xx (-19/7)xx5/8`
`= -1xx5/8`
`=-5/8`
D)
`3/7xx9/11+3/7xx2/11`
`=3/7xx(9/11+2/11)`
`=3/7xx11/11`
`=3/7xx1`
`=3/7`
Tính:
a) \(\dfrac{2}{5}\times\dfrac{3}{8}\times\dfrac{3}{4}\) b) \(\dfrac{1}{3}\times\dfrac{1}{6}\times\dfrac{1}{9}\)
c) \(\dfrac{3}{4}:\dfrac{1}{5}:\dfrac{7}{8}\) d) \(\dfrac{3}{5}:\dfrac{1}{5}:\dfrac{1}{8}\)
a) $\frac{2}{5} \times \frac{3}{8} \times \frac{3}{4} = \frac{{2 \times 3 \times 3}}{{5 \times 8 \times 4}} = \frac{{18}}{{160}} = \frac{9}{{80}}$
b) $\frac{1}{3} \times \frac{1}{6} \times \frac{1}{9} = \frac{{1 \times 1 \times 1}}{{3 \times 6 \times 9}} = \frac{1}{{162}}$
c) $\frac{3}{4}:\frac{1}{5}:\frac{7}{8} = \frac{3}{4} \times \frac{5}{1} \times \frac{8}{7} = \frac{{3 \times 5 \times 8}}{{4 \times 1 \times 7}} = \frac{{120}}{{28}} = \frac{{30}}{7}$
d) $\frac{3}{5}:\frac{1}{5}:\frac{3}{8} = \frac{3}{5} \times \frac{5}{1} \times \frac{8}{3} = \frac{{3 \times 5 \times 8}}{{5 \times 1 \times 3}} = 8$
B= \(\dfrac{\dfrac{2}{3}\times\dfrac{17}{3}-\dfrac{2}{3}\times\dfrac{4}{13}+\dfrac{7}{3}}{\dfrac{9}{2}-\dfrac{9}{4}-\dfrac{9}{5}}\)
Giải hộ với ạ!
\(B=\dfrac{\dfrac{2}{3}\left(\dfrac{17}{3}-\dfrac{4}{13}\right)+\dfrac{7}{3}}{\dfrac{9}{20}}=3:\dfrac{9}{20}=3\cdot\dfrac{20}{9}=\dfrac{60}{9}=\dfrac{20}{3}\)
\(B=\dfrac{\dfrac{2}{3}\times\left(\dfrac{17}{3}-\dfrac{4}{13}\right)+\dfrac{7}{3}}{\dfrac{9}{2}-\dfrac{9}{4}-\dfrac{9}{5}}=\dfrac{\dfrac{2}{3}\times1+\dfrac{7}{3}}{\dfrac{9.10-9.5-9.4}{20}}\\ =\dfrac{\dfrac{2}{3}+\dfrac{7}{3}}{\dfrac{90-45-36}{20}}=\dfrac{\dfrac{9}{3}}{\dfrac{9}{20}}=\dfrac{9}{3}\times\dfrac{20}{9}=\dfrac{20}{3}\)
Tính.
a) \(\dfrac{4}{7}\times\dfrac{3}{5}\) b) \(\dfrac{1}{3}\times\dfrac{9}{10}\) c) \(\dfrac{1}{6}\times\dfrac{1}{4}\)
a) \(\dfrac{4}{7}\times\dfrac{3}{5}=\dfrac{4\times3}{7\times5}=\dfrac{12}{35}\)
b) \(\dfrac{1}{3}\times\dfrac{9}{10}=\dfrac{1\times9}{3\times10}=\dfrac{9}{30}=\dfrac{3}{10}\)
c) \(\dfrac{1}{6}\times\dfrac{1}{4}=\dfrac{1}{4\times6}=\dfrac{1}{24}\)
\(\dfrac{5}{9}\times\dfrac{7}{13}+\dfrac{5}{9}\times\dfrac{8}{13}-\dfrac{5}{13}\times\dfrac{2}{9}\)
`5 / 9 xx 7 / 13 + 5 / 9 xx 8 / 13 - 5 / 13 xx 2 / 9`
`=5 / 9 xx 7 / 13 + 5 / 9 xx 8 / 13 - 5 / 9 xx 2 / 13`
`= 5 / 9 xx ( 7 / 13 + 8 / 13 - 2 / 13 )`
`= 5 / 9 xx 13 / 13 = 5 / 9`
Tính:
a) \(\dfrac{9}{5}+\dfrac{2}{5}\times\dfrac{4}{6}\)
b) \(\dfrac{3}{8}\times2-\dfrac{6}{7}\times\dfrac{1}{3}\)
Số?
a) \(\dfrac{3}{5}=\dfrac{3\times4}{5\times4}=\dfrac{?}{?}\) \(\dfrac{2}{7}=\dfrac{2\times?}{7\times3}=\dfrac{?}{?}\)
b) \(\dfrac{9}{12}=\dfrac{9:3}{12:3}=\dfrac{?}{?}\) \(\dfrac{18}{24}=\dfrac{18:6}{24:?}=\dfrac{?}{?}\)
a) \(\dfrac{12}{20}\)
b)\(\dfrac{6}{21}\)
c)\(\dfrac{3}{4}\)
d) 6 ; \(\dfrac{3}{4}\)
a) \(\dfrac{-2}{15}\times x=\dfrac{-2}{7}\) b) \(\dfrac{7}{-5}\times x=-3\) c) \(-\dfrac{4}{9}x=\dfrac{1}{2}\) d) \(\dfrac{8}{3}\div x=\dfrac{-3}{8}\)
e) \(x\div\dfrac{3}{-4}=-12\) f) \(\left(-1\right)\div x=\dfrac{-3}{7}+\dfrac{4}{5}\) g)\(\dfrac{4}{11}x-\dfrac{1}{3}=\dfrac{2}{5}\) i) \(\dfrac{-6}{7}-\dfrac{1}{5}x=-4\)
j) \(\dfrac{1}{2}+\dfrac{2}{3}\div7=\dfrac{-1}{3}\) k) \(\dfrac{-5}{2}+x\div7=\dfrac{-1}{3}\) L) \(\dfrac{-3}{2}-\dfrac{1}{4}\div x=-1\)
a: =>x*2/15=2/7
=>x=2/7:2/15=2/7*15/2=15/7
b: x=3:7/5=15/7
c: x=-1/2:4/9=-1/2*9/4=-9/8
d: x=-8/3:3/8=-64/9
g: =>4/11x=2/5+1/3=6/15+5/15=11/15
=>x=11/15:4/11=121/60
l: =>1/4:x=1-3/2=-1/2
=>x=-1/4:1/2=-1/4*2=-1/2
k: =>x:7=-1/3+5/2=-2/6+15/6=13/6
=>x=91/6
1. tìm x thuộc z biết \(\dfrac{x}{-12}\)=\(\dfrac{-3}{2}\)
2 tính
a,\(\dfrac{-7}{9}\times\dfrac{6}{11}+\dfrac{-2}{9}\)
b,\(\dfrac{-4}{7}:2=\)
c,115- (24-5\(\times\)3)
d,\(\dfrac{-3}{7}\times\dfrac{5}{9}+\dfrac{4}{9}\times\dfrac{-3}{7}+2\dfrac{3}{7}\)
e,\(\dfrac{1}{4\times5}+\dfrac{1}{6\times7}+......\dfrac{1}{79\times80}\)
1,
x =( -12 . ( -3) ) : 2
x = 18
2,
a, -7/9 . 6/11 + (-2/9) = -14/33 + (-2/9) = -64/99
b, -4/7 : 2 = -4/7 . 1/2 = -2/7
c, 115 - (24 - 5. 3) = 115 - ( 24 - 15) = 115 - 9 = 106
d,= -3/7. (5/9 + 4/9) + 17/7 = -3/7 . 1 +17/7 = -3/7 . 17/7 = -51/49
e, ??? mình cx k biết
Lời giải:
\(\dfrac{x}{-12}=\dfrac{-3}{2}\)
\(\Rightarrow2x=-12.\left(-3\right)\)
\(\Rightarrow2x=36\)
\(\Rightarrow x=18\)
Tính:
a) \(\dfrac{3}{5}\times\dfrac{6}{7}\) b) \(\dfrac{2}{9}\text{×}\dfrac{18}{3}\) c) \(\dfrac{5}{7}\text{×}12\) d) \(21\text{×}\dfrac{2}{7}\)
a) $\frac{3}{5} \times \frac{6}{7} = \frac{{3 \times 6}}{{5 \times 7}} = \frac{{18}}{{35}}$
b) $\frac{2}{9} \times \frac{{18}}{3} = \frac{{2 \times 18}}{{9 \times 3}} = \frac{{36}}{{27}} = \frac{4}{3}$
c) $\frac{5}{7} \times 12 = \frac{{5 \times 12}}{7} = \frac{{60}}{7}$
d) $21 \times \frac{2}{7} = \frac{{21 \times 2}}{7} = \frac{{42}}{7} = 6$