3/7 + 2/5
5/6 + 3
41/42 - 3/7
4/5 - 1/2
Những câu hỏi liên quan
1. 1/30×29-1/29×28-1/28×27-...-1/3×2-1/2×1
2. 1/2×3+1/2×2+2/4×6+3/7×9+4/9×13+5/13×18+6/18×24
3. 8/6+14/12+22/20+32/30+44/42+58/56+74/72+92/90
1: \(=\dfrac{1}{29\cdot30}-\left(\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+...+\dfrac{1}{28\cdot29}\right)\)
\(=\dfrac{1}{29\cdot30}-\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{28}-\dfrac{1}{29}\right)\)
\(=\dfrac{1}{29\cdot30}-\dfrac{28}{29}=\dfrac{1-28\cdot30}{870}=\dfrac{-859}{870}\)
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Tìm x, biết:
a) x + 99:3 = 55
b) (x - 25): 15=20
c) (3.x - 15).7 = 42
d) (8x - 16)(x-5)=0
e) x.(x+1)=2+4+6+8+10+...+2500
a, \(x\) + 99: 3 = 55
\(x\) + 33 = 55
\(x\) = 55 - 33
\(x\) = 22
b, (\(x\) - 25):15 = 20
\(x\) - 25 = 20 x 15
\(x\) - 25 = 300
\(x\) = 300 + 25
\(x\) = 325
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c, (3\(x\) - 15).7 = 42
3\(x\) - 15 = 42:7
3\(x\) - 15 = 6
3\(x\) = 6 + 15
3\(x\) = 21
\(x\) = 21: 3
\(x\) = 7
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d, (8\(x\) - 16).(\(x\) -5) = 0
\(\left[{}\begin{matrix}8x-16=0\\x-5=0\end{matrix}\right.\)
\(\left[{}\begin{matrix}8x=16\\x=5\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=16:8\\x=5\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=2\\x=5\end{matrix}\right.\)
Vậy \(x\) \(\in\) {2; 5}
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7\3 + 1\2 + -16\32
65\91 + -33\55
36\-84 + 109\450
4/20 + 16\42 + 6\10 + -3\5 + 2\21 + -10\21 + 3\10
5\12 + 3\-16 + 3\4
giải hộ mik với nha
5/6 của 74 là:
A.42/20 B.21/10 C.2 1/10 D.cả 3 câu trên đều đúng.
Tính nhanh:
1) 69.(− 74)−31.74
2) (− 2020).35− 2020.65
3) − 23.59 −159.23
4) −147.47+ (− 47).(− 47)−300
5) (− 72).30 −31.−30 + 3.+ 30
6) (−82).(−55)+ (−82)+ (− 46).(−82)
7) (− 41).135+135.(− 24)−35.(−65)
8) 125.( 2) .( 25).9.( 10) .4 3 0 − − −
9) ( 2) .( 25).( 125).( 2) .2.( 50) 2 3 − − + − −
10) 125.(−88)
1, 69. (-74) - 31 . 74
= (-69) . 74 - 31 . 74
= 74(-69 - 31)
= 74(-100)
= -7400
2, (-2020) . 35 - 2020 . 65
= 2020 . (-35) - 2020 . 65
= 2020(-35 - 65)
= 2020(-100)
= -202000
3, -23 . 59 - 159 . 23
= 23 . (-59) - 159 . 23
= 23(-59 - 159)
= 23 . (-218)
= -5014
4, -147 . 47 + (-47)(-47) - 300
= -147 . 47 + 47 . 47 - 300
= 47(-147 + 47) - 300
= 47 . (-100) - 300
= -4700 - 300
= -5000
5, (-72) . 30 - 31 . (-30) + 3 + 30
= (-72) . 30 + 31 . 30 + 3 + 30
= 30(-72 + 31 + 1) + 3
= 30 . (-40) + 3
= -1200 + 3
= -1197
6, (-82)(-55) + (-82) + (-46)(-82)
= (-82)(-55 + 1 - 46)
= (-82)(-100)
= 8200
7, (-41) . 135 + 135 . (-24) - 35 . (-65)
= 135(-41 - 24) - 35(-65)
= 135(-65) - 35(-65)
= (-65)(135 - 35)
= -65(100)
= -6500
10, 125 . (-88)
= 1000 . \(\frac{1}{8}\) . (-88)
= 1000 . (-11)
= -11000
Câu 8 với 9 mình ko hiểu nên ko giúp bn được
Chúc bạn học tốt!
3/7 x 6/7
4 x 5/7
4/11 : 2/7
3/5 : 7
Tính rồi viết (theo mẫu):a)25 : 5 42 : 2 99 : 3............ ............ ....................... ............ ....................... ............ ...........b)30 : 4 38 : 5 49 : 6............ ............ ....................... ............ ....................... ............ ...........a)26 : 3 32 : 4 60 : 6 55 : 5............ ............ ........... .......
Đọc tiếp
Tính rồi viết (theo mẫu):
a)25 : 5 42 : 2 99 : 3
............ ............ ...........
............ ............ ...........
............ ............ ...........
b)30 : 4 38 : 5 49 : 6
............ ............ ...........
............ ............ ...........
............ ............ ...........
a)26 : 3 32 : 4 60 : 6 55 : 5
............ ............ ........... ...........
............ ............ ........... ...........
Bài 1:
a) (6-2/3+1/2)-(5+5/3-2/3)-(3-7/3+5/2)
b)(-1/1/2:1,25)+(10/3/7:5/3/14)
c)(-2/3+1/7):121/42
a) \(\left(6-\frac{2}{3}+\frac{1}{2}\right)\)- \(\left(5+\frac{5}{3}-\frac{2}{3}\right)\)- \(\left(3-\frac{7}{3}+\frac{5}{2}\right)\)
= \(6-\frac{2}{3}+\frac{1}{2}-5-\frac{5}{3}+\frac{2}{3}-3+\frac{7}{3}-\frac{5}{2}\)
= \(-2+\frac{2}{3}-\frac{4}{2}\)
= \(\frac{-12}{6}+\frac{4}{6}-\frac{12}{6}\)= \(\frac{4}{6}=\frac{2}{3}\)
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a/\(\left(6-\frac{2}{3}+\frac{1}{2}\right)-\left(5+\frac{5}{3}-\frac{2}{3}\right)-\left(3-\frac{7}{3}+\frac{5}{2}\right)..\)
\(=\left(6-\frac{1}{6}\right)-\left(5+1\right)-\left(3-\frac{-1}{6}\right)\)
\(=6-\frac{1}{6}-\left(5+1\right)-3-\frac{1}{6}\)
\(=\left[6-\left(5+1\right)\right]-\frac{1}{6}-\frac{1}{6}-3\)
\(=0-\frac{1}{6}-\frac{1}{6}-3\)
\(=\frac{-1}{6}-\frac{1}{6}-3\)
\(=\frac{-10}{3}\)
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\(\left(\frac{-1}{\frac{1}{2}}:1,25\right)+\left(\frac{10}{\frac{3}{7}}:\frac{5}{\frac{3}{14}}\right)\)
\(=\left(-2:1,25\right)+\left(\frac{70}{3}:\frac{70}{3}\right)\)
\(=\frac{-8}{5}+1=\frac{-3}{5}\)
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Tính hợp lí(nếu có thể): a, A=35.73-135.27+35.27-73.153
b,B=96.7 mũ 2-37.7 mũ 2+15.7 mũ 2-49.174
c,C=2/7.(22/19-12/51)+2/7.(-3/19+ âm 2/7)
d, D=1/2+5/6+11/12+19/20+29/30+41/42+55/56+71/72+89/90