13/15-(x-13/21):4/7=3 4/5-3,6
Tính theo mẫu :
Mẫu : 13/21 + 5/7 = 13/21 + 5 x 3 / 7 x 3 = 13/21 + 15/21 = 28/21
26/81 + 4/27
5/64 + 7/8
\(\dfrac{26}{81}+\dfrac{4}{27}=\dfrac{26+12}{81}=\dfrac{38}{81}\)
\(\dfrac{5}{64}+\dfrac{7}{8}=\dfrac{5+56}{64}=\dfrac{61}{64}\)
\(\dfrac{26}{81}+\dfrac{4}{27}=\dfrac{26}{81}+\dfrac{4\times3}{27\times3}=\dfrac{26}{81}+\dfrac{12}{81}=\dfrac{38}{81}\)
\(\dfrac{5}{64}+\dfrac{7}{8}=\dfrac{5}{64}+\dfrac{7\times8}{8\times8}=\dfrac{5}{64}+\dfrac{56}{64}=\dfrac{61}{64}\)
1,5 x {-2/25}
13/5 x -3/4
-15/4 : 21/-1
{-21/7} : {-11/14}
` 1, 5 . ( -2/25 = 3/2 . (-2)/25 = -6/50 = -3/25 `
` 1 3/5 . (-3)/4 = 8/5 . (-3)/4 = -24/20 = -6/5 `
`-15/4 : 21/(-1) = -15/4 . (-1)/21 = 15/84 = 5/28 `
` ( -2 1/7 ) : ( -1 1/14 ) = (-15)/7 : (-15)/14 = -15/7 . (-14)/15 = 210/105 = 2 `
`@animephamdanhv.`
2/3 + 3/4
9/4 + 3/5
5/24 + 1/4
3/15 - 5/35 18/27 - 2/6 37/12 - 3
11/9 x 3/22 7/13 x 13/7 4 x6/7
2/5 : 3/10 3/8 : 9/4 8/21 : 4/7
2/3 + 3/4=17/12
9/4 + 3/5=57/20
5/24 + 1/4=11/24
3/15 - 5/35=2/35 18/27 - 2/6=1/3 37/12 - 3=1/12
11/9 x 3/22=1/6 7/13 x 13/7=1 4 x6/7=24/7
2/5 : 3/10=4/3 3/8 : 9/4=1/6 8/21 : 4/7=2/3
2/3 + 3/4
= 17/12
9/4 + 3/5
= 57/20
5/24 + 1/4
=11/24
3/15 - 5/35
=2/35
18/27 - 2/6
=1/3
37/12 - 3
= 1/12
11/9 x 3/22
=1/6
7/13 x 13/7
=1
4 x6/7
=24/7
2/5 : 3/10
=4/3
3/8 : 9/4
=1/6
8/21 : 4/7
= 2/3
1=17/12
2=57/20
3=11/24
4=2/35 7=1/3 10=1/12
5=1/6 8=1 11=24/7
6=4/3 9=1/6 12=2/3
a) x - = b) . c)
) : e) f) .
x
x
d x x x x x
3 13 2 4 3 7 2
1 3
5 25 3 5 10 15 3
4 5 1 7 2 11 1 1
3 15 1 3
5 7 6 5 5 2 3 2
17/19 x 12/15 x 19/17 (5/7 + 9/7)x 21/18
4/5 x 13/14 + 13/14 x 1/5
a: \(=\dfrac{17}{19}\cdot\dfrac{19}{17}\cdot\dfrac{4}{5}=\dfrac{4}{5}\)
b: \(=\dfrac{14}{7}\cdot\dfrac{7}{6}=2\cdot\dfrac{7}{6}=\dfrac{14}{6}=\dfrac{7}{3}\)
c: =13/14(4/5+1/5)=13/14
17/19 x 12/15 x 19/17 (5/7 + 9/7)x 21/18
4/5 x 13/14 + 13/14 x 1/5
\(\dfrac{17}{19}\times\dfrac{12}{15}\times\dfrac{19}{17}=\dfrac{12}{15}\)
\(\left(\dfrac{5}{7}+\dfrac{9}{7}\right)\times\dfrac{21}{18}=2\times\dfrac{7}{6}=\dfrac{7}{3}\)
\(\dfrac{4}{5}\times\dfrac{13}{14}+\dfrac{13}{14}\times\dfrac{1}{5}=\dfrac{13}{14}\)
17/19 x 12/15 x 19/17 (5/7 + 9/7)x 21/18
4/5 x 13/14 + 13/14 x 1/5
\(\dfrac{17}{19}\times\dfrac{12}{15}\times\dfrac{19}{17}.\\ =\dfrac{17}{19}\times\dfrac{19}{17}\times\dfrac{12}{15}.\\ =1\times\dfrac{12}{15}=\dfrac{12}{15}.\\ \left(\dfrac{5}{7}+\dfrac{9}{7}\right)\times\dfrac{21}{18}.\\ =2\times\dfrac{7}{6}=\dfrac{7}{3}.\\ \dfrac{4}{5}\times\dfrac{13}{14}+\dfrac{13}{14}\times\dfrac{1}{5}.\\ =\left(\dfrac{4}{5}+\dfrac{1}{5}\right)\times\dfrac{13}{14}.\\ =1\times\dfrac{13}{14}.\\ =\dfrac{13}{14}.\)
Bài 1 Tính nhanh
a) -3/7 + 5/13 + 3/7
b) -5/21+-2/21+8/24
c) -5/11+(-6/11+2)
d) (-1/32+1/2)+15/32
e)5/17+ -6/13 + 3/4 + 7/-13+12/17
f) 7/23+-18/18+-4/9+16/23+-5/8
g)1/3+-3/4+3/5+-1/36+1/15+-2/9
h)-1/2+1/3+-1/4+-2/8+4/18+4/9
a)\(-\dfrac{3}{7}+\dfrac{5}{13}+\dfrac{3}{7}\)
=\(\left(-\dfrac{3}{7}+\dfrac{3}{7}\right)+\dfrac{5}{13}\)
=\(0+\dfrac{5}{13}\)
=\(\dfrac{5}{13}\)
Tính
a, -(-5)-(+7)+(+3)+(-8)
b, -(-15)-|-10|+|-9|-|5|
c, 14-(-13)-(17)+(-12)
d, -|-14| + |-10| - (-12) + (-8)
e, -(-11) + (-15) + (13) - 21
Bài 2 tìm x
1, -x + 20 = - (-15) - (8) + 13
2, -(-10) + x = -13 + (-9) + (-6)
3, 8-(-12) + 10 = - (-14) - x
4. - (+12) + (-x) - (-3) = 5 - (-7)
5. 14 - x + (-10) = - (-9) + (+15)
6. 12 - (-17) + (-3) = -5 + x
7. X - (-19) - (+32) = 14 - (+16)
8. X - |-15| - |7| = - (-9) + |-5|
9. 15 - x + 17 = 13 - (-21)
10. - |-5| - (-x) +4 = 3 - (-25)
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bài1
a,
5 - 7 + 3 +(-8)
= -2 + 3 + ( - 8)
= 1 + (-8)= -7
a; - (-5) - (+7) + (+3) + (-8)
= 5 - 7 + 3 - 8
= (5 + 3 - 8) - 7
= (8 - 8) - 7
= 0 - 7
= - 7