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a, 64 . 23 + 37 . 23 - 23
= 23. (64 + 37 - 1)
= 23 . 100
=2300
b, 33,76 + 19,52 + 6,24
= (33,76 + 6,24) + 19,52
= 40 + 19,52
= 59,52
c, 38/11 + (16/13 + 6/11)
= 38/11 + 16/13 + 6/11
= (38/11 + 6/11) + 16/13
= 4 + 16/13
= 52/13 + 16/13
= 68/13
d, 3/4 : 3/5 - 1/5
= 3/4 . 5/3 - 1/5
= 5/4 - 1/5
= 25/20 - 4/20
= 21/20
e, \(5\frac{3}{4}\div\frac{12}{13}+6\frac{1}{4}\div\frac{12}{13}\)
\(=\frac{23}{4}\cdot\frac{13}{12}+\frac{25}{4}\cdot\frac{13}{12}\)
\(=\frac{13}{12}\cdot\left(\frac{23}{4}+\frac{25}{4}\right)\)
\(=\frac{13}{12}\cdot12=13\)
f, S = 1 + 2 + 3 + 4 + ... + 99 + 100
Số số hạng của S là :
(100 - 1) : 1 + 1 = 100 (số hạng)
Tổng của S là :
(1 + 100) . 100 : 2 = 5050
Vậy S = 5050
Dấu " . " là dấu nhân nhé :D
a: =>3/5-x+13/20=5/6
=>11/10-x=5/6
=>x=11/10-5/6=4/15
b: =>x=4/9+5/9=1
c: =>3/2-2x=16/3:8/3=2
=>2x=-1/2
=>x=-1/4
d: =>x+1,5=-5/8*8/5=-1
=>x=-2,5
`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`
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
\(3\frac{1}{4}x-\frac{7}{6}x=\frac{-5}{12}+\frac{12}{3}\)
= \(\frac{13}{4}x-\frac{7}{6}x=\frac{-5}{12}+\frac{12}{3}\)
= \(x.\left(\frac{13}{4}-\frac{7}{6}\right)=\frac{43}{12}\)
= \(x.\frac{25}{12}=\frac{45}{12}\)
\(x=\frac{45}{12}:\frac{25}{12}\)
\(x=\frac{9}{5}\)
\(3\frac{1}{4}x-\frac{7}{6}x=-\frac{5}{12}+\frac{12}{3}\)
\(\frac{13}{4}x-\frac{7}{6}x=-\frac{5}{12}+\frac{48}{12}\)
\(\left(\frac{13}{4}-\frac{7}{6}\right)x=\frac{43}{12}\)
\(\frac{25}{12}x=\frac{43}{12}\)
\(x=\frac{43}{25}\)
\(4\dfrac{3}{4}+\left(-0,37\right)+\dfrac{1}{8}+\left(-2,5\right)+5\dfrac{1}{2}\)
\(=\dfrac{19}{4}-0,37+\dfrac{1}{8}-\dfrac{5}{2}+\dfrac{11}{2}\)
=\(\left(\dfrac{19}{4}+\dfrac{1}{8}\right)+\left(-\dfrac{5}{2}+\dfrac{11}{2}\right)-0,37\)
=\(\dfrac{39}{8}+3-0,37\)
= 4,875+3-0,37
= 7,505