Tính hợp lí :
B = 5 / 2 x1 + 4 / 1x 11 + 3 / 11 x 2 + 1 /2x15 + 13 / 15 x 4
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Những câu hỏi liên quan
5 tháng 3 2022
a,\(\frac{1}{5}\times\frac{2}{9}\div\frac{1}{15}\)
\(=\frac{1}{5}\times\frac{2}{9}\times15\)
\(=\left(\frac{1}{5}\times15\right)\times\frac{2}{9}\)
\(=3\times\frac{2}{9}\)
\(=\frac{2}{3}\)
b\(\frac{4}{15}\times\frac{7}{15}\times\frac{5}{4}\)
\(=\left(\frac{4}{15}\times\frac{5}{4}\right)\times\frac{7}{15}\)
\(=\frac{1}{3}\times\frac{7}{15}\)
\(=\frac{7}{45}\)
c,\(\frac{21}{23}\times\frac{5}{11}\times\frac{44}{?}\)
d,\(26\times\frac{13}{42}\div13\)
\(=\left(26\div13\right)\times\frac{13}{42}\)
\(=2\times\frac{13}{42}\)
\(=\frac{13}{21}\)
VQ
24 tháng 9 2023
\(a,1\dfrac{4}{7}.3\dfrac{4}{11}.3\dfrac{11}{15}.5\dfrac{5}{8}\)
\(=\dfrac{11}{7}.\dfrac{27}{11}.\dfrac{56}{15}.\dfrac{45}{8}\)
\(=\dfrac{11.27.56.45}{7.11.15.8}\)
\(=\dfrac{1.3.7.3}{1.1.1.1}\)
\(=63\)
\(b,\dfrac{3}{4}.1\dfrac{1}{2}+\dfrac{3}{4}.\dfrac{1}{2}\)
\(=\dfrac{3}{4}.\left(1\dfrac{1}{2}+\dfrac{1}{2}\right)\)
\(=\dfrac{3}{4}.2\)
\(=\dfrac{3}{2}\)
C
28 tháng 2 2023
`a)3/5+(-4/9)`
`=3/5-4/9`
`=27/45-20/45`
`=7/45`
`b)3/5+2/5 . 15/8`
`=3/5 + 30/40`
`=3/5+3/4`
`=12/20+15/20`
`=27/20`
`c)7/2 . 8/13 + 8/13 . (-5/2)`
`=8/13 . (7/2 +(-5)/2)`
`=8/13 . 1`
`=8/13`
`d)-5/17 . (-9/23)+9/23 . (-22/17) + 11 9/23`
`=-5/17 . (-9/23) + 9/23 . (-1) . 22/17 + 11 + 9/23`
`=-5/17 . (-9/23) + (-9/23) . 22/17+11+9/23`
`= -9/23 ( -5/17 + 22/17)+11+9/23`
`= - 9/23 . 1+11+9/23`
`=-9/23+11+9/23`
`=(-9/23+9/23)+11`
`=0+11`
`=11`
28 tháng 2 2023
a: =27/45-20/45=7/45
b: =3/5+30/40
=3/5+3/4
=12/20+15/20
=27/20
c: =8/13(7/2-5/2+1)=8/13*2=16/13
d: =9/23*5/17-9/23*22/17+11+9/23
=-9/23+11+9/23
=11
29 tháng 4 2019
A = ( -4/5 + 4/3 ) + (-5/4 + 14/5) - 7/3
= 8/15 + 31/20 - 7/3
= 25/12 - 7/3
= -1/4
B = 8/3 x 2/5 x 3/8 x 10x 19/92
= 16/15 x 15/4 x 19/92
= 4x19/92
= 19/23
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
22 tháng 9
C = - \(\dfrac{5}{7}\) x \(\dfrac{2}{11}\) + \(\dfrac{-5}{7}\) x \(\dfrac{9}{14}\) + \(\dfrac{1}{57}\)
= - \(\dfrac{10}{77}\) - \(\dfrac{45}{98}\) + \(\dfrac{1}{57}\)
= - \(\dfrac{635}{1078}\) + \(\dfrac{1}{57}\)
= - \(\dfrac{36195}{61446}\) + \(\dfrac{1078}{61446}\)
= - \(\dfrac{35117}{61446}\)
trả lời:
B = 7x( 5/2x7 + 4/7x11 + 3/11x14 + 1/14x15 + 13/15x28 )
B = 7x(1/2 - 1/7 + 1/7 - 1/11 +....+ 1/15 - 1/28)
B = 7x(1/2 - 1/28)
B = 7x13/28
B = 13/4
Bàì làm:
\(B=\frac{5}{2.1}+\frac{4}{1.11}+\frac{3}{11.2}+\frac{1}{2.15}+\frac{13}{15.4}\)
\(B=7.\left(\frac{5}{2.7}+\frac{4}{7.11}+\frac{3}{11.14}+\frac{1}{14.15}+\frac{13}{15.28}\right)\)
\(B=7.\left(\frac{1}{2}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+\frac{1}{14}-\frac{1}{15}+\frac{1}{15}-\frac{1}{28}\right)\)
\(B=7.\left(\frac{1}{2}-\frac{1}{28}\right)\)
\(B=7.\frac{13}{28}\)
\(B=\frac{13}{4}\)