1+2+3+...+x=55
a) x/14 - 1/7 = -3/4
b) x -1/8 =5/8
c) 1/5 + 1/11 < x/55 < 2/5 + 1/55 mà x thuộc z
a) Ta có: \(\dfrac{x}{14}-\dfrac{1}{7}=\dfrac{-3}{4}\)
\(\Leftrightarrow\dfrac{x}{14}=\dfrac{-3}{4}+\dfrac{1}{7}=\dfrac{-21}{28}+\dfrac{4}{28}=\dfrac{-17}{28}\)
hay \(x=\dfrac{-17\cdot14}{28}=\dfrac{-17}{2}\)
Vậy: \(x=-\dfrac{17}{2}\)
\(a)\dfrac{x}{14}-\dfrac{1}{7}=\dfrac{-3}{4}\)
\(\dfrac{x}{14}=\dfrac{-3}{4}+\dfrac{1}{7}\)
\(\dfrac{x}{14}= \dfrac{-17}{28}\)
\(x=\dfrac{14.(-17)}{28}\)
\(x=\dfrac{-17}{2}\)
\(b)x-\dfrac{1}{8}=\dfrac{5}{8}\)
\(x=\dfrac{5}{8}+\dfrac{1}{8}\)
\(x=\dfrac{6}{8}=\dfrac{3}{4}\)
\(c)\dfrac{1}{5}+\dfrac{1}{11}<\dfrac{x}{55}<\dfrac{2}{5}+\dfrac{1}{55}(xthuộc Z )\)
\(\Rightarrow \dfrac{11}{55}+\dfrac{5}{55}<\dfrac{x}{55}<\dfrac{22}{55}+\dfrac{1}{55} \)
\(\Rightarrow \dfrac{16}{55}<\dfrac{x}{55}<\dfrac{23}{55}\)
\(\Rightarrow 21< x < 23\)
\(\Rightarrow x=22\)
Bài 2.Tìm x
d,155-10(x+1)=55
e,6(x+2^3)+40=100
f,2^2(x+3^2)-5=55
d,155-10(x+1)=55
10(x+1) = 155 - 55
10(x+1) = 100
x+1 = 100 : 10
x+1 = 10
x = 10 - 1 =9
e,6(x+\(2^3\))+40=100
6(x+\(2^3\)) = 100 - 40
6(x+\(2^3\)) = 60
(x+\(2^3\)) = 60 : 6
(x+\(2^3\)) = 10
x = 10 - \(2^3\)
x = 10 - 8 = 2
f,\(2^2\)(x+\(3^2\))-5=55
\(2^2\)(x+\(3^2\)) = 55 + 5
\(2^2\)(x+\(3^2\)) = 60
(x+\(3^2\)) = 60 : \(2^2\)
(x+\(3^2\)) = 60 : 4
(x+\(3^2\)) = 15
x + 9 = 15
x = 15-9=6.
Hok tốt !
d) \(155-10\left(x+1\right)=55\)
\(\Rightarrow10\left(x+1\right)=155-55\)
\(\Rightarrow10\left(x+1\right)=100\)
\(\Rightarrow x+1=100:10\)
\(\Rightarrow x+1=10\)
\(\Rightarrow x=10-1\)
\(\Rightarrow x=9\)
Vậy x = 9
e) \(6\left(x+2^3\right)+40=100\)
\(\Rightarrow6\left(x+2^3\right)=100-40\)
\(\Rightarrow6\left(x+2^3\right)=60\)
\(\Rightarrow x+2^3=60:6\)
\(\Rightarrow x+2^3=10\)
\(\Rightarrow x+8=10\)
\(\Rightarrow x=10-8\)
\(\Rightarrow x=2\)
Vậy x = 2
f) \(2^2\left(x+3^2\right)-5=55\)
\(\Rightarrow2^2\left(x+3^2\right)=55+5\)
\(\Rightarrow2^2\left(x+3^2\right)=60\)
\(\Rightarrow4\left(x+9\right)=60\)
\(\Rightarrow x+9=60:4\)
\(\Rightarrow x+9=15\)
\(\Rightarrow x=15-9\)
\(\Rightarrow x=6\)
Vậy x = 6
\(d,155-10\left(x+1\right)=55\) \(e,6\left(x+2^3\right)+40=100\)
\(\Rightarrow10\left(x+1\right)=155-55\) \(\Rightarrow\left(x+2^3\right)+40=100:6\)
\(\Rightarrow10\left(x+1\right)=100\) ủa hình như câu này sai đề thì phải ??-.-'''
\(\Rightarrow x+1=100:10\)
\(\Rightarrow x+1=10\)
\(\Rightarrow x=10-1=9\)
1. 55 x 30 x 2 + 110 x 50 + 55 x 40 / 24 x 47 +8 x 23 x 3 + 3 x 30 x 8
2. 9,6 : (1,32 +3,48) - 0,5 + 1 1/2 x 2 3/4 - 1 1/2 x 1 1/4
(lam cho mik vs .Mik cam on)
1.\(\frac{43141}{3}\)
2.18
=14380,333333333333
=18
(*<>*)
tìm x, biết :
a) 1/( x+1 ).( x+2 ) + 1/( x+2 ).( x+3 ) + 1/( x+3 ).( x+4 ) + ... + 1/( x+1999).( x+2000) = 1/x+200 = 1/5
b) 2/( x+1 ).( x+3 ) + 3/( x+3 ) .( x+6 ) + 4/( x+6 ).( x+10 ) + ... + 10/( x+45 ).( x+55 ) + 1/ x+55 = 1/6
22(x+32)-5=55
155-10(x+1)=55
5.22+(x+3)=52
53-5(4+x)=15
a/ 22(x + 32) - 5 = 55 b/ 155 - 10(x+1) = 55
4(x + 32) = 60 10(x + 1) = 100
x + 32 = 60 : 4 x + 1 = 10
x + 32 = 15 x = 10 - 1
x = 15 - 32 x = 9
x = - 17
c/ 5. 22 + (x+3) = 52 53 - 5 (4 + x) = 15
20 + (x+3) = 25 125 - 5(4 +x) = 15
x+ 3 = 5 5(4 + x) = 110
x = 5-3 4 + x= 110 : 2
x = 2 4 + x = 55
x = 51
ủng hộ mk nha !!!! ^_^
Tìm x thuộc Z :
a/1/5+2/11<x/55<2/5+1/55
b/x/21=4/7+(-7)/3
= 11/55+ 10/55<x/55<2/5+1/55
=2/5<x/55<23/55
=22/55<x/55<23/55
=> x thuộc rỗng
x/21=4/7+(-7)/3
= x/21=12/21+(-49)/21
= x/21=-37/21
=> x = -37
tính:
1 + 3 + 6 + 10 +....+ 45 + 55/ 1 x 10 + 2 x 9 + 3 x 8 +...+ 8 x 3 + 9 x 2 + 10 x 1
(x+1)+(x+2)+(x+3)+........+(x+55)=1650
(x + 1) + (x + 2) + (x + 3) +........+ (x + 55) = 1540
=> 55x + ( 1 + 2 + .... + 55) = 1540
=> 55x + 1485 = 1540
=> 55x = 110
=> x = 2
Nastu_Draneel ơi, Nếu theo những con số mà bạn nguyễn vân anh ghi thiếu thì phải là như thế này chứ
(x+1)+(x+2)+(x+3)+...+(x+55)=1540
<=>(1+2+3+...+55)+55x=1540
<=>(55+1).55:2+55x=1540
<=>1540+55x=1540
=>55x=0
=>x=0
( 1/2 x 2/1 - 2/3 x 3/2 + 3/4 x 4/3 - 100/101 x 101/100 + 55 ) x x = aa