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\(\dfrac{3}{7}\times\dfrac{7}{9}\times\dfrac{1}{2}\)
\(=\dfrac{3\times7\times1}{7\times9\times2}\)
\(=\dfrac{21}{126}\)
\(=\dfrac{1}{6}\)
\(\dfrac{5}{8}\times4\times\dfrac{1}{2}\\ =\dfrac{5}{8}\times\dfrac{4}{1}\times\dfrac{1}{2}\\ =\dfrac{5\times4\times1}{8\times1\times2}\\ =\dfrac{20}{16}\\ =\dfrac{5}{4}\)
\(4\times\dfrac{1}{24}\times3\\ =\dfrac{4}{1}\times\dfrac{1}{24}\times\dfrac{3}{1}\\ =\dfrac{4\times1\times3}{1\times24\times1}\\ =\dfrac{12}{24}\\ =\dfrac{1}{2}\)
2 : \(buổi \) \(sáng\) \(bán\) \(dc :\)
\((360 - 142 : 2 =109 l\)
\(buổi\) \(chiều\) \(bán\) \(dc :\)
\(360 - 109 = 251 l\)
\(1,\)
\(a,x\times\dfrac{3}{9}=\dfrac{9}{15}\) \(b,x:\dfrac{1}{2}=\dfrac{5}{6}\)
\(x=\dfrac{9}{15}:\dfrac{3}{9}\) \(x=\dfrac{6}{5}\times\dfrac{1}{2}\)
\(x=\dfrac{81}{45}=\dfrac{9}{5}\) \(x=\dfrac{6}{10}=\dfrac{3}{5}\)
\(2,\) có bạn làm rồi nhé ;>
\(3,\)
\(a,\dfrac{7}{12}+\dfrac{3}{4}\times\dfrac{2}{9}=\dfrac{7}{12}+\left(\dfrac{3}{4}\times\dfrac{2}{9}\right)=\dfrac{7}{12}+\dfrac{1}{6}=\dfrac{7}{12}+\dfrac{2}{12}=\dfrac{7+2}{12}=\dfrac{9}{12}=\dfrac{3}{4}\)
\(b,\dfrac{8}{9}-\dfrac{4}{15}:\dfrac{2}{5}=\dfrac{8}{9}-\left(\dfrac{4}{15}:\dfrac{2}{5}\right)=\dfrac{8}{9}-\dfrac{2}{3}=\dfrac{8}{9}-\dfrac{6}{9}=\dfrac{8-6}{9}=\dfrac{2}{9}\)
a) \(\dfrac{6}{7}+\dfrac{7}{8}=\dfrac{48}{56}+\dfrac{49}{56}=\dfrac{97}{56}\)
b) \(\dfrac{4}{5}-\dfrac{2}{3}=\dfrac{12}{15}-\dfrac{10}{15}=\dfrac{2}{15}\)
c) \(\dfrac{2}{3}.\dfrac{4}{9}=\dfrac{8}{27}\)
d) \(\dfrac{1}{5}:\dfrac{2}{7}=\dfrac{1}{5}.\dfrac{7}{2}=\dfrac{7}{10}\)
a: =48/56+49/56
=97/56
b: =12/15-10/15
=2/15
c: =(2*4)/(3*9)=8/27
d: =1/5*7/2=7/10
3: Số học sinh giỏi là 40*1/5=8 bạn
Số học sinh trung bình là 32*3/8=12 bạn
Số học sinh khá là 32-12=20 bạn
1:
a: -1/3+7/6=7/6-2/6=5/6
b: 5/7-3/5=25/35-21/35=4/35
c: 0,75*4/5=4/5*3/4=3/5
a) 4 + 5/7 = .... 28/7 + 5/7=.33/7..............
5/9 x 6/7 = ..10/21....
3 - 7/5 = 15/5 - 7/5...8/5........
3/5 x 4/8 = ..3/10....
b) 2 - 1/4 = .8/4 - 1/4...7/4...
4 : 5/9 = ..4 x 9/5 = 36/5....
2/9 x 3/5 = .....2/15.....
3/8 : 4 = ......3/8 x 1/4 = 3/2.....
b: Ta có: \(1992+\left(-53\right)+158+\left(-247\right)+\left(-1592\right)\)
\(=\left(1992-1592\right)+\left(-53-247\right)+158\)
\(=400-300+158=258\)
nhiều quá :((
\(a,2\left(x-5\right)-3\left(x+7\right)=14\)
\(2x-10-3x-21=14\)
\(-x-31=14\)
\(-x=45\)
\(x=45\)
\(b,5\left(x-6\right)-2\left(x+3\right)=12\)
\(5x-30-2x-6=12\)
\(3x-36==12\)
\(3x=48\)
\(x=16\)
\(c,3\left(x-4\right)-\left(8-x\right)=12\)
\(3x-12-8+x=0\)
\(4x-20=0\)
\(4x=20\)
\(x=5\)
Cố nốt nha bn !
cảm ơn, bn nha:)))
mà hình như bạn TOP 3 trả lời câu hỏi pải ko nhỉ???
a) 5 x 3 + 15 = 15 + 15
= 30
b) 4 x 7 – 28 = 28 – 28
= 0
c) 2 x 1 x 8 = 2 x 8
= 16