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Bài 6:
a: \(x=-\dfrac{2}{3}-\dfrac{1}{7}=\dfrac{-14-3}{21}=\dfrac{-17}{21}\)
d: \(x=\dfrac{9}{10}\cdot\dfrac{-5}{9}=\dfrac{-1}{2}\)
e: \(\Leftrightarrow x\cdot\dfrac{1}{3}=\dfrac{14}{21}-\dfrac{3}{21}=\dfrac{11}{21}\)
=>x=11/7
1)
a) 35.23 + 35.41 + 64.65 = 35(23+41) + 64.65 = 35 . 65 + 64.65 =65. 99 = 65(100 - 1 ) = 6500 - 65 = 6435
b) 29.87 - 29.23 + 64.71 = 29(87-23) + 64.71 = 29.64 + 64.71 = 64(71+29) = 64.100= 6400
c) 48.19 + 48.115 + 134.52 = 48(19+115) + 134.52 = 48 . 134+134.52=134(52+48)=134.100=13400
d) 27.121 - 87.27 + 73.34 = 27(121-87) +73 .34 = 27 .34 + 73.34 = 34(73+27)=34.100=3400
e) 125.98-125.46-52.25 = 125(98-46) -52.25 = 125 . 52 - 52.25 =52(125-25) =52.100=5200
f)136.23 + 136.17 - 40.36 = 136(23+17) - 40.36 = 136.40 -40.36 = (136-36)40 = 100.40=4000
g) 17.93 + 116.83 + 17.23 = 17(93+23) + 116.83 = 17.116 + 116.83 =116(83+17) = 116.100=11600
h)19.27 +47.81 + 19.20 = 19(27+20) + 47.81 = 19. 47 + 47.81 = 47(81+19)=47.100 = 4700
i) 87.23 + 13.93 + 70.87 = 87(23+70) + 13.93 = 87 .93 + 13.93 = 93(87+13)=93.100=9300
2)Tìm x
a) [(6x-39):37].4 = 12
(6x - 39) : 37 = 12 : 4 = 3
x =(3.37 + 39): 6 = 25
b) ( x : 3 - 4 ) .5=15
x : 3 -4 = 3
x = (3+4).3 = 21
c) 128 - 3(x+4) =23
3x + 12 = 128 -23 = 105
x = (105-12):3 = 31
d) (3x - 34).73=2.74
3x - 81 = 2.74:73=2.7=14
x =(81 + 14 ) : 3= \(31\frac{2}{3}\)
e) x - [42 + (-28) ] = -8
x - 14 = -8
x- 14 + 14 = -8 + 14
x = 6
g. \(\left(x+\frac{1}{2}\right)\left(\frac{2}{3}-2x\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x+\frac{1}{2}=0\\\frac{2}{3}-2x=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=\frac{-1}{2}\\x=\frac{1}{3}\end{cases}}\)
Vậy \(x\in\left\{\frac{-1}{2};\frac{1}{3}\right\}\)
f. \(\frac{2}{3}x-\frac{1}{2}x=\frac{5}{12}\)
\(\Leftrightarrow x\left(\frac{2}{3}-\frac{1}{2}\right)=\frac{5}{12}\)
\(\Leftrightarrow x\left(\frac{4}{6}-\frac{3}{6}\right)=\frac{5}{12}\)
\(\Leftrightarrow\frac{1}{6}x=\frac{5}{12}\)
\(\Leftrightarrow x=\frac{5}{12}\div\frac{1}{6}\)
\(\Leftrightarrow x=\frac{30}{12}=\frac{5}{2}\)
a) 3/7 + 4/9 + 4/7 + 5/9
= ( 3/7 + 4/7 ) + ( 4/9 + 5/9 )
= 7/7 + 9/9
= 1 + 1
= 2
b)1/5 + 4/10 + 9/15 + 16/20 + 25/25 + 36/30 + 49/35 + 64/40 + 81/45
= 1/5 + 2/5 + 3/5 + 4/5 + 5/5 + 6/5 + 7/5 + 8/5 + 9/5
= ( 1/5 + 9/5 ) + ( 2/5 + 8/5 ) + (7/5 + 3/5 ) + ( 4/5 + 6/5 ) + 5/5
= 2 + 2 + 2 + 2 + 1
= 2 x 4 + 1
= 8 +1
= 9
c) 1/8 + 1/12 + 3/8 + 5/12
= ( 1/8 + 3/8 ) + ( 1/12 + 5/12)
= 4/8 + 6/12
= 1/2 + 1/2
= 2/4 = 1/2
mỏi tay rồi
d; (1 - \(\dfrac{1}{2}\)) x (1 - \(\dfrac{1}{3}\)) x (1 - \(\dfrac{1}{4}\)) x ... x ( 1 - \(\dfrac{1}{100}\))
= \(\dfrac{1}{2}\) x \(\dfrac{2}{3}\) x \(\dfrac{3}{4}\) x \(\dfrac{3}{4}\) x ... x \(\dfrac{99}{100}\)
= \(\dfrac{1}{100}\)
các bn lm đến đâu cx dc miễn là lm hộ mk cái ạ, ai đang lm vào nhắn tin vs mk để mk bít nha
a; \(-\dfrac{8}{3}+\dfrac{7}{5}-\dfrac{71}{15}< x< -\dfrac{13}{7}+\dfrac{19}{14}-\dfrac{7}{2}\)
-\(\dfrac{19}{15}\) - \(\dfrac{71}{15}\) < \(x\) < -\(\dfrac{1}{2}\) - \(\dfrac{7}{2}\)
-6 < \(x\) < -4
vì \(x\) \(\in\) Z nên \(x\) = -5
1. Tính nhanh:
a, 35.23+35.41+64.65
= 35. (23+41) +64.65
= 35. 64 + 64.65
= 64. ( 35 + 65 )
= 64 . 100
= 6400
b, 29.87 - 29.23 + 64.71
= 29.(87-23) + 64.71
= 29.64 + 64.71
= 64.(29 + 71)
= 64.100
= 6400
c, 48.19 + 48.115 + 134.52
= 48.(19 + 115) + 134.52
= 48.134 + 134.52
= 134.(48 + 52)
= 134.100
= 13400
d, 27.121 - 87.27 + 73.34
= 27.(121 - 87) + 73.34
= 27.34 + 73.34
= 34.(27 + 73)
= 34.100
= 3400
e, 125.98 - 125.46 - 52.25
= 125.(98 - 46) - 52.25
= 125.52 - 52.25
= 52.(125 - 25)
= 52.100
= 5200
f, 136.23 + 136.17 - 40.36
= 136.(23 + 17) - 40.36
= 136.40 - 40.36
= 40.(136 - 36)
= 40.100
= 4000
g, 17.93 + 116.83 + 17.23
= 17.(93+23) + 116.83
= 17.116 + 116.83
= 116.(17 + 83)
= 116.100
= 11600
Lát nữa mình làm tiếp, giờ mình phải đi học rồi
Bài 1 :
a/ \(a^3.a^9=a^{3+9}=a^{12}\)
b/\(\left(a^5\right)^7=a^{5.7}=a^{35}\)
c/ \(\left(a^6\right).4.a^{12}=a^{24}.a^{12}.4=a^{24+12}.4=a^{36}.4\)
d/ \(\left(2^3\right)^5.\left(2^3\right)^3=2^{15}.2^9=2^{15+9}=2^{24}\)
e/ \(5^6:5^3+3^3.3^2\)
\(=5^3+3^5=125+243=368\)
i/ \(4.5^2-2.3^2\)
\(=2^2.5^2-2.3^2\)
\(=2^2.25-2^2.14\)
\(=2^2.\left(25-14\right)\)
\(=2^2.11\)
\(=4.11=44\)
a)\(\dfrac{3}{10}\)-x=\(\dfrac{25}{30}\)-\(\dfrac{4}{30}\)
\(\dfrac{3}{10}-x=\dfrac{7}{10}\)
x = \(\dfrac{3}{10}-\dfrac{7}{10}\)
x=\(\dfrac{-4}{10}\)
b)\(\dfrac{-5}{8}+x=\dfrac{4}{9}-\dfrac{63}{9}\)
\(\dfrac{-5}{9}+x=\dfrac{-59}{9}\)
\(x=\dfrac{-59}{9}-\dfrac{-5}{9}\)
\(x=\dfrac{-64}{9}\)
c)=>2.18=(x-3).(x-3)
=>36=(x-3)\(^2\)
=>6\(^2\)=(x-3)\(^2\)
6= x-3
x=6+3=9
a, -25+37
= 12
d, 8 - (5-7)
= 8 - (-2)
= 10
cảm ơn bn nhưng làm thêm giùm mk với chứ bây giờ mk chưa k cho bn đc