(−8):140=−6:(−7x)
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\(14\times32+7\times140-28\)
\(=14\times32+7\times10\times14-2\times14\)
\(=14\times\left(32+70-2\right)\)
\(=14\times100\)
\(=1400\)
Rut gon :
2x -6/8-6/56-6/140-6/260=43/52
2x-12/13 =43/52
2x =43/52+12/13
x = 7/4 : 2
x = 7/8
ta có A=\(\dfrac{6}{8}\)+\(\dfrac{6}{56}\)+\(\dfrac{6}{140}\)+...+\(\dfrac{6}{1100}\)+\(\dfrac{6}{1400}\)
=\(\dfrac{3}{4}\)+\(\dfrac{3}{28}\)+\(\dfrac{3}{70}\)+...+\(\dfrac{3}{550}\)+\(\dfrac{3}{700}\)
=\(\dfrac{3}{1.4}\)+\(\dfrac{3}{4.7}\)+\(\dfrac{3}{7.10}\)+...+\(\dfrac{3}{22.25}\)+\(\dfrac{3}{25.28}\)
=1-\(\dfrac{1}{4}\)+\(\dfrac{1}{4}\)-\(\dfrac{1}{7}\)+\(\dfrac{1}{7}\)-\(\dfrac{1}{10}\)+...+\(\dfrac{1}{22}\)-\(\dfrac{1}{25}\)+\(\dfrac{1}{25}\)-\(\dfrac{1}{28}\)
=1-\(\dfrac{1}{28}\)
=\(\dfrac{27}{28}\)
Vậy A=\(\dfrac{27}{28}\)
Ta có:
A =6/8+6/56+6/140+...+6/1100+6/1400
⇒A=3/4+3/28+3/70+...+3/550+3/700
⇒A=3/1.4+3/4.7+3/7.10+...+3/22.25+3/25.28
⇒A=1−1/4+1/4−1/7+1/7−1/10+...+1/22−1/25+1/25−1/28
⇒A=1−1/28
⇒A=1-1/38
= 3+ 8 = 11 - 4 = 7 + 11= 18 - 6 =12 + ...(= +3) = 15 + 140= 290 - 92 = 198
= ( 5 - 2) + ( 8 - 4 ) + (11 -6) +...+ (140 - 92)
= 3 + 4 + 5 + ... + 48
Dãy số trên có số số hạng là:
( 48 - 3) : 1 + 1 = 46 số
Tổng các số là:
( 48 + 1) x 46 : 2 = 1127
137+4 (2x+3)=200(hình như đề bài sai)
200-6(x-5)=140
6(x-5)=200-140
6(x-5)=60
x-5=60:6
x-5=10
x=10+5
x=15
140:(x-8)=7
x-8=140:7
x-8=20
x=20+8
x=28
137+4(2x+3)=200
4(2x+3)=200-137
4(2x+3)=63
2x+3=63:4
2x+3=\(\frac{63}{4}\)
2x=\(\frac{63}{4}\)-3
2x=\(\frac{51}{4}\)
x=\(\frac{51}{4}\):2
x=\(\frac{51}{8}\)
Vậy ...
200-6(x-5)=140
6(x-5)=200-140
6(x-5)=60
x-5=60:6
x-5=10
x=15
Vậy...
140:(x-8)=7
x-8=140:7
x-8=20
x=20+8
x=28
Vậy...
k mik nhé
Rốt cuộc YC tìm gì
\(\text{(−8):140=−6:(−7x)}\)
\(\Rightarrow\text{-6:(−8):140=(−7x)}\)
\(\Rightarrow105=-7x\)
\(\Rightarrow x=\frac{105}{-7}=-15\)
\(\text{Vậy }x=-15\)