a) 2.3x =162
3x =162:2
3x=81
3x=34
vậy x bằng 4
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HA
27 tháng 7 2017 lúc 10:12
bài 1 tìm x
aleft(3x-15right)3^7div3^5
bleft(4x+32right)43times2^2
c 6^{2x-7}216
d 5^x+5^{x+2}650
eleft(3x-7right)^481
bài 2 tính a ,b,c, biết
a, a+b12,b+c18,c+a-4
b,atimes bdfrac{5}{6},btimes cdfrac{6}{7},ctimes adfrac{5}{7}
c,2a-3b+4c24và1adfrac{3}{4}bdfrac{1}{3}c
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bài 1 tìm x
a\(\left(3x-15\right)=3^7\div3^5\)
b\(\left(4x+32\right)=43\times2^2\)
c \(6^{2x-7}=216\)
d \(5^x+5^{x+2}=650\)
e\(\left(3x-7\right)^4=81\)
bài 2 tính a ,b,c, biết
a, \(a+b=12,b+c=18,c+a=-4\)
b,\(a\times b=\dfrac{5}{6},b\times c=\dfrac{6}{7},c\times a=\dfrac{5}{7}\)
c,\(2a-3b+4c=24\)và\(1a=\dfrac{3}{4}b=\dfrac{1}{3}c\)
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tìm x:
a) \(-8:\left(4\dfrac{1}{5}x+\dfrac{3}{10}\right)=4\dfrac{4}{9}\)
b) \(4\dfrac{2}{3}-\left(\dfrac{3}{5}:x\right)=-20\%\)
c) \(\left(\dfrac{13}{10}x-15\right).-\dfrac{5}{14}=3\)
d) \(\left(5,5x-44\right):\left(-\dfrac{3}{2}\right)=30\)
e) \(\dfrac{11}{14}:\left(2x+\dfrac{5}{7}\right)=-\dfrac{11}{18}\)
Giúp mình với
1. Thực hiện phép tính (Tính nhanh nếu có thể):
a) left(dfrac{3}{8}+dfrac{-4}{3}+dfrac{7}{12}right)divdfrac{5}{6}+dfrac{1}{2}
b) 0,5times11dfrac{1}{3}times75%divdfrac{2}{5}+dfrac{3}{5}
c) -5^2-4dfrac{1}{2}left(10,6-1dfrac{3}{5}right)+75%
d) left(-3,2right)timesdfrac{-15}{64}+left(0,8-2dfrac{4}{15}right)div3dfrac{2}{3}
e) dfrac{-3}{5}timesdfrac{2}{7}+dfrac{-3}{5}timesdfrac{5}{7}+2dfrac{3}{5}
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Giúp mình với 
1. Thực hiện phép tính (Tính nhanh nếu có thể):
a) \(\left(\dfrac{3}{8}+\dfrac{-4}{3}+\dfrac{7}{12}\right)\div\dfrac{5}{6}+\dfrac{1}{2}\)
b) \(0,5\times11\dfrac{1}{3}\times75\%\div\dfrac{2}{5}+\dfrac{3}{5}\)
c) \(-5^2-4\dfrac{1}{2}\left(10,6-1\dfrac{3}{5}\right)+75\%\)
d) \(\left(-3,2\right)\times\dfrac{-15}{64}+\left(0,8-2\dfrac{4}{15}\right)\div3\dfrac{2}{3}\)
e) \(\dfrac{-3}{5}\times\dfrac{2}{7}+\dfrac{-3}{5}\times\dfrac{5}{7}+2\dfrac{3}{5}\)
Tìm số nguyên x
1/ 17x+3left(-16x-37right)2x+43-4x
2/ -2x-3left(x-17right)34-2left(-x+25right)
3/ left{-3x+2left[45-x-3left(3x+7right)-2xright]+4xright}55-103-57:left[-2left(2x-1right)^2-left(-9right)^0right]-106
4/ -2x+3left{12-2left[3x-left(20+2xright)-4xright]+1right}45
5/ 3x-32-5+1
6/ 15+4x 2x-145
7/ -3left(2x+5right)-16 -4left(3-2xright)
8/ -2x+15 3x-7 19-x
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Tìm số nguyên x
1/ \(17x+3\left(-16x-37\right)=2x+43-4x\)
2/ \(-2x-3\left(x-17\right)=34-2\left(-x+25\right)\)
3/ \(\left\{-3x+2\left[45-x-3\left(3x+7\right)-2x\right]+4x\right\}=55-103-57:\left[-2\left(2x-1\right)^2-\left(-9\right)^0\right]=-106\)
4/ \(-2x+3\left\{12-2\left[3x-\left(20+2x\right)-4x\right]+1\right\}=45\)
5/ \(3x-32>-5+1\)
6/ \(15+4x< 2x-145\)
7/ \(-3\left(2x+5\right)-16< -4\left(3-2x\right)\)
8/ \(-2x+15< 3x-7< 19-x\)
tìm x:
a)\(\left(x+\dfrac{1}{2}\right).\left(\dfrac{2}{3}-2x\right)=0\)
b) \(\left(x.6\dfrac{2}{7}+\dfrac{3}{7}\right).2\dfrac{1}{5}-\dfrac{3}{7}=-2\)
c) \(x.3\dfrac{1}{4}+\left(\dfrac{-7}{6}\right).x-1\dfrac{2}{3}=\dfrac{5}{12}\)
d) \(5\dfrac{8}{17}:x+\left(-\dfrac{4}{17}\right):x+3\dfrac{1}{7}:17\dfrac{1}{3}=\dfrac{4}{11}\)
Câu 1 : Tìm x :
a) \(\left(-11\right)^2-15.\left(x-2\right)=134-16x\)
b) \(\left(4x+1\right)\left(x^2-16\right)=0\)
c) \(-2\left(x-3\right)+\left(-2\right)^2=4-3x\)
Bài 1: Tính:
Aleft(-2right).left(-3right)-5.left|-5right|+125.left(dfrac{-1}{5}right)^2
Bleft(-3right).left|-7right|-left(-4right).left|5right|+dfrac{1}{3}.left|-9right|
Cleft(-2right)^3.left|-3right|-dfrac{1}{5}.left|-25right|-4.left|-7right|+left(-2right)^2
Dleft(-6right).left|-3right|+2.left|-9right|-7left|left(-2right)^3right|+8.left|-7right|
Eleft|-3^2right|.left|4right|-left|7right|.8-left|6right|.left|-8right|-left|12right|.left(dfrac{1}{2}right)^2
Bài 2: Tìm x:
a)12-2left|3x+2rig...
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Bài 1: Tính:
A=\(\left(-2\right).\left(-3\right)-5.\left|-5\right|+125.\left(\dfrac{-1}{5}\right)^2\)
B=\(\left(-3\right).\left|-7\right|-\left(-4\right).\left|5\right|+\dfrac{1}{3}.\left|-9\right|\)
C=\(\left(-2\right)^3.\left|-3\right|-\dfrac{1}{5}.\left|-25\right|-4.\left|-7\right|+\left(-2\right)^2\)
D=\(\left(-6\right).\left|-3\right|+2.\left|-9\right|-7\left|\left(-2\right)^3\right|+8.\left|-7\right|\)
E=\(\left|-3^2\right|.\left|4\right|-\left|7\right|.8-\left|6\right|.\left|-8\right|-\left|12\right|.\left(\dfrac{1}{2}\right)^2\)
Bài 2: Tìm x:
a)\(12-2\left|3x+2\right|=10\)
b)\(2.\left|5-4x\right|+17=\left(-2\right)^3.\left(-4\right)\)
c)\(\left|3x-5\right|+\left(-3\right)^2.2=12.\left|3x+5\right|+117\)
d)\(4.\left|3-2x\right|+\left(-5\right).\left|4-3x\right|-5=-6\)
e)\(\left|2x-7\right|-2^3.\left|2x-7\right|+15=-5.\left|2x-7\right|+3\)
f)\(\left|x+2\right|+\left|x^2-4\right|=0\)
g)\(\left|3x-9\right|+\left|x^2-9\right|=0\)
h)\(\left|2x-1\right|+\left|x^2-\dfrac{1}{4}\right|=0\)
Cho đẳng thức :\(x\times\left(x+1\right)\times\left(x+2\right)\times.............\times\left(x+2016\right)=2016\)(với x>0)
Chứng tỏ rằng \(x< \dfrac{1}{2015!}\)
HA
12 tháng 8 2017 lúc 8:43
thực hiện phép tính
a,dfrac{2}{3}-dfrac{3}{5}divleft(-1dfrac{1}{5}right)+left(dfrac{-2}{3}right)timesdfrac{3}{8}
b,17dfrac{11}{9}-left(6dfrac{3}{13}+7dfrac{11}{19}right)+left(10dfrac{3}{13}-5dfrac{1}{4}right)
c,left(dfrac{-3}{2}right)^2-left[-2dfrac{1}{3}-left(dfrac{3}{4}+dfrac{1}{3}right)div2dfrac{3}{5}right]timesleft(dfrac{-3}{4}right)
d,dfrac{21}{33}divdfrac{11}{5}-dfrac{13}{33}divdfrac{11}{5}+dfrac{25}{33}divdfrac{11}{5}+dfrac{6}{11}
giúp mình nhé
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thực hiện phép tính
a,\(\dfrac{2}{3}-\dfrac{3}{5}\div\left(-1\dfrac{1}{5}\right)+\left(\dfrac{-2}{3}\right)\times\dfrac{3}{8}\)
b,\(17\dfrac{11}{9}-\left(6\dfrac{3}{13}+7\dfrac{11}{19}\right)+\left(10\dfrac{3}{13}-5\dfrac{1}{4}\right)\)
c,\(\left(\dfrac{-3}{2}\right)^2-\left[-2\dfrac{1}{3}-\left(\dfrac{3}{4}+\dfrac{1}{3}\right)\div2\dfrac{3}{5}\right]\times\left(\dfrac{-3}{4}\right)\)
d,\(\dfrac{21}{33}\div\dfrac{11}{5}-\dfrac{13}{33}\div\dfrac{11}{5}+\dfrac{25}{33}\div\dfrac{11}{5}+\dfrac{6}{11}\)
giúp mình nhé