1/2×3 + 1/ 3×4 + 1/4×5 + ........ + 1/ X- 1×X= 504/ 1009
Tìm X
giúp với ạ:
bài 1: tính tổng các số nguyên biết:
1) -20 < x < 21
2) -18 ≤ x ≤ 17
3) -27 < x ≤ 27
4) /x/ ≤ 3
5) /-x/ < 5
bài 2: tính tổng:
1) 1 + (-2) +3+(-4)+....+19+(-20)
2) 1-2+3-4+....+99-100
3) 2-4+6-8+....+48-50
4) -1+3-5+7-...+97-99
5) 1+2-3-4+...+97+98-99-100
Bài 1:
a: Tổng là:
(-19+19)+(-18+18)+...+20=20
b: Tổng là:
-18+(-17+17)+...+0=-18
x-5/1007+x-3/504=x-1/2018+x-4/403
bạn tách từng câu ra mik suy nghĩ từng câu
\(\frac{x-3}{504}+\frac{x-5}{1007}=\frac{x-1}{2018}+\frac{x-4}{403}\)
\(\frac{x-3}{504}+\frac{x-5}{1007}=\frac{x-1}{2018}+\frac{x-4}{403}\)
<=> \(\frac{x-3}{504}-4+\frac{x-5}{1007}-2=\frac{x-1}{2018}-1+\frac{x-4}{403}-5\)
<=> \(\frac{x-2019}{504}+\frac{x-2019}{1007}=\frac{x-2019}{2018}+\frac{x-2019}{403}\)
<=> \(\left(x-2019\right)\left(\frac{1}{504}+\frac{1}{1007}-\frac{1}{2018}-\frac{1}{403}\right)=0\)
<=> x - 2019 = 0
( vì \(\frac{1}{504}+\frac{1}{1007}-\frac{1}{2018}-\frac{1}{403}\ne0\))
<=> x = 2019
vậy x = 2019.
1) 168 - ( 18 - 2x ) x 12 = 120
2) [ 75 + ( 16 - x ) ] x 2 = 156
3) 124 - 24 x ( 3x - 16 ) = 76
4) [ ( 10 - x ) x 2 + 5 ] : 3 - 2 = 3
5) [ 80 + ( 62 - x ) ] : 17 - 7 = 1
6) 65 - ( 5x - 70 ) : 2 = 50
7) 504 : 9 136 - 2x ) + 4 = 32
8) ( 13x - 28 ) x 15 - 5 x 23 = 320
Mình cần gấp ạ !!!
1. Tìm x
23+24+.............+2x=504
Đặt A = 23 + 24 + ... + 2x
=> 2A = 24 + 25 + ... + 2x + 1
Khi đó 2A - A = (24 + 25 + ... + 2x + 1) - (23 + 24 + ... + 2x)
=> A = 2x + 1 - 23 = 2x + 1 - 8
Khi đó 23 + 24 + ... 2x = 504
<=> 2x + 1 - 8 = 504
=> 2x + 1 = 512
=> 2x + 1 = 29
=> x + 1 = 9
=> x = 8
Vậy x = 8
Giải phương trình sau:
\(\frac{x+1}{507}+\frac{x+2}{506}+\frac{x+3}{505}=\frac{x+4}{504}+\frac{x+5}{503}+\frac{x-6}{604}\)
a,1/3 .(x-2/5)=3/4 b, 7/3:(x-2/3)=4/5 c,1/3.(x-2/5)=4/5 d, 2/3.(x-1/2)-1/4.(x-2/5)=7/3 e,3/7 .(x-2/3)+1/2=5/4.(x-2) f,1/2.(x-3)+1/3.(x-4)+1/4.(x-5)=1/5 g,[2/3.(x-1/2)-4/5]:(x-1/3)=21/5 h, {x-[1/2.(x-3)+11/5]}:(x-1/2)=3/5 i,x.(x-2/5)-(x+2).x+11/4=4/3
a: =>x-2/5=3/4:1/3=3/4*3=9/4
=>x=9/4+2/5=45/20+8/20=53/20
b: =>x-2/3=7/3:4/5=7/3*5/4=35/12
=>x=35/12+2/3=43/12
c: 1/3(x-2/5)=4/5
=>x-2/5=4/5*3=12/5
=>x=12/5+2/5=14/5
d: =>2/3x-1/3-1/4x+1/10=7/3
=>5/12x-7/30=7/3
=>5/12x=7/3+7/30=77/30
=>x=77/30:5/12=154/25
e: \(\Leftrightarrow x\cdot\dfrac{3}{7}-\dfrac{2}{7}+\dfrac{1}{2}-\dfrac{5}{4}x+\dfrac{5}{2}=0\)
=>\(x\cdot\dfrac{-23}{28}=\dfrac{2}{7}-3=\dfrac{-19}{7}\)
=>x=19/7:23/28=76/23
f: =>1/2x-3/2+1/3x-4/3+1/4x-5/4=1/5
=>13/12x=1/5+3/2+4/3+5/4=257/60
=>x=257/65
i: =>x^2-2/5x-x^2-2x+11/4=4/3
=>-12/5x=4/3-11/4=-17/12
=>x=17/12:12/5=85/144
1) (3x-2)/3-2=(4x+1)/4
2) (x-3)/4+(2x-1)/3=(2-x)/6
3) 1/2 (x+1)+1/4 (x+3)=3-1/3 (x+2)
4) (x+4)/5-x+4=x/3-(x-2)/2
5) (4-5x)/6=2(-x+1)/2
6) (-(x-3))/2-2=5(x+2)/4
7)2(2x+1)/5-(6+x)/3=(5-4x)/15
8) (7-3x)/2-(5+x)/5=1
9)(x-1)/2+3(x+1)/8=(11-5x)/3
10)(3+5x)/5-3=(9x-3)/4