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\(\Leftrightarrow\dfrac{1}{2}\left(\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{x}-\dfrac{1}{x+1}\right)=\dfrac{505}{1011}\)
\(\Leftrightarrow\dfrac{1}{2}-\dfrac{1}{x+1}=\dfrac{1010}{1011}\)
=>1/x+1=-1009/2022
=>x+1=-2022/1009
hay x=-3031/1009
x + (x + 1) + (x + 2) + ... + (x + 2022) + 2022 = 2022
x + x + x + ... + x + 1 + 2 + 3 + ... + 2022 + 2022 = 2022 (1)
Số số hạng x:
2022 - 0 + 1 = 2023 (số)
Từ (1) ta có:
2023x + 2022.2023 : 2 + 2022 = 2022
2023x + 2045253 = 2022 - 2022
2023x = 0 - 2045253
2023x = -2045253
x = -2045253 : 2023
x = -1011
Ta có : x + (x + 1) + (x + 2) + ... + (x+2022) + 2022 = 2022
=> x + (x + 1) + (x + 2) + ... + (x + 2022) = 2022 - 2022
=> [x + (x + 2022) ] . { [ (x + 2022) - x) : 1 + 1] } : 2 = 0
( số đầu + số cuối . số số hạng : 2 )
=> (2x + 2022) . 2023 : 2 = 0
=> 2x + 2022 = 0 . 2 : 2023= 0
=> (2x + 2022) : 2 = 0 : 2
=> x + 1011 = 0 => x = -1011
a )Ta có :
|x + 1| ≥ 0
|x + 2| ≥ 0
|x + 3| ≥ 0
.......
|x + 10| ≥ 0
=> |x + 1| + |x + 2 | + .... + |x + 10| ≥ 0
Mà |x + 1| + |x + 2 | + .... + |x + 10| = 11x
=> 11x ≥ 0 => x ≥ 0
Vì x ≥ 0 => |x + 1| + |x + 2 | + .... + |x + 10| = x + 1 + x + 2 + ... + x + 10 = 11x
=> 10x + 55 = 11x => 11x - 10x = 55 => x = 55
b ) 2(x + 1) - 4(x - 3) = 2017
<=> 2x + 2 - 4x + 12 = 2017
<=> 2x - 4x + 2 + 12 = 2017
<=> - 2x + 14 = 2017
<=> -2x = 2003
=> x = -1001.5
a, | x+9| + | y - 31 |=0
|x + 9| > 0; |y - 31| > 0
=> | x+ 9| =0 và |y - 31| = 0
=> x + 9 = 0 và y - 31 = 0
=> x = -9 và y = 31
b,| x+1 | +|x+2| +.......+ | x+10| = 11x
|x + 1|; |x + 2|;...;|x + 10| > 0
=> |x + 1| + |x + 2| + ... + |x + 10| > 0
=> 11x > 0
=> x > 0
=> x + 1 + x + 2+ ... + x + 10 = 11x
=> 10x + 55 = 11x
=> 11x - 10x = 55
=> x = 55
c,(x-5)2 + (x+10)2 < 0
tương tự phần a
(\(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+...+\dfrac{1}{2023}\)). x = (\(\dfrac{2021}{2}+1\))+(\(\dfrac{2020}{3}+1\))+....+(\(\dfrac{1}{2022}+1\))
(\(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+...+\dfrac{1}{2023}\)). x = \(\dfrac{2023}{2}\)+\(\dfrac{2023}{3}\)+....+ \(\dfrac{2023}{2022}\)
(\(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+...+\dfrac{1}{2023}\)). x = 2023.( \(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+...+\dfrac{1}{2023}\))
vậy x= 2023
\(\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+...+\dfrac{1}{x\left(x+1\right)}=\dfrac{2022}{2023}\)
\(\Rightarrow1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{x}-\dfrac{1}{x+1}=\dfrac{2022}{2023}\)
\(\Rightarrow1-\dfrac{1}{x+1}=\dfrac{2022}{2023}\)
\(\Rightarrow\dfrac{1}{x+1}=1-\dfrac{2022}{2023}\)
\(\Rightarrow\dfrac{1}{x+1}=\dfrac{1}{2023}\)
\(\Rightarrow x+1=2023\)
\(\Rightarrow x=2022\)
Vậy x = 2022
#kễnh
\(\dfrac{1}{1.2}+\dfrac{1}{2.3}+...+\dfrac{1}{x.\left(x+1\right)}\)
= \(\dfrac{2-1}{1.2}+\dfrac{3-2}{2.3}+...+\dfrac{x+1-x}{x.\left(x+1\right)}\)
= \(\dfrac{2}{1.2}-\dfrac{1}{1.2}+\dfrac{3}{2.3}-\dfrac{2}{2.3}+...+\dfrac{x+1}{x.\left(x+1\right)}-\dfrac{x}{x.\left(x+1\right)}\)
= \(\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{x}-\dfrac{1}{x+1}\)
= \(1-\dfrac{1}{x+1}\) =\(\dfrac{2022}{2023}\)
= \(\dfrac{2023}{2023}-\dfrac{1}{x+1}=\dfrac{2022}{2023}\)
⇒ \(x+1=2023\)
\(x=2023-1=2022\)
\(a,2\left(x-5\right)-3\left(x+7\right)=14\)
\(\Leftrightarrow2x-10-3x-21=14\)
\(\Leftrightarrow-x-31=14\Leftrightarrow-x=45\Leftrightarrow x=-45\)
\(c,5\left(x-6\right)-2\left(x+3\right)=12\)
\(\Leftrightarrow5x-30-2x-6=12\)
\(\Leftrightarrow3x-36=12\Leftrightarrow3x=48\Leftrightarrow x=16\)
Các câu còn lại tương tự
a, 2(x - 5) - 3(x + 7) = 14\(\Rightarrow2\chi-10-3\chi+21=14\Rightarrow2\chi-3\chi=14+10-21\)
\(\Rightarrow-\chi=3\Rightarrow\chi=3\)
\(-5.\left(2-x\right)+4\left(x-3\right)=10x+15\)
\(-10+5x+4x-12=10x+15\)
\(9x-22=10x+15\)
\(10x-9x=-22-15\)
\(x=-37\)
\(7.\left(x-9\right)-5\left(6-x\right)=-6+11x\)
\(7x-63-30+5x=-6+11x\)
\(12x-93=-6+11x\)
\(12x-11x=-6+93\)
\(x=87\)
\(xy+14+2y+7x=-10\)
\(\left(xy+2y\right)+\left(14+7x\right)=-10\)
\(y\left(x+2\right)+7\left(2+x\right)=-10\)
\(\left(x+2\right)\left(y+7\right)=-10\)
Câu cuối mk chỉ biết làm đến đó thôi
bn tự làm nha
a, ( 13.x - 122) : 5 = 5
( 13.x - 122) = 5.5
( 13.x - 122) = 25
( 13.x - 144) = 25
13.x = 25 + 144
13.x = 169
x = 169 : 13
x = 13
Vậy x = 13
b, 3.x[82 - 2.(25 - 1)] = 2022
3.x[64 - 2.(32 - 1)] = 2022
3.x[62 - 2.31] = 2022
3.x[62 - 62] = 2022
3.x.0 = 2022
3.x = 2022 : 0
3.x = 0
x = 0 : 3
x = 0
Vậy x = 0
Đây bạn nhé !!!
Chúc bạn học tốt !!!
11x - 2.10 mũ 3 = -2022
11x - 2.1000 = -2022
11x - 2 = -2022 : 1000
11x - 2 = -2.022
11x = - 2.022 + 2
11x = -0.022
x = -0.022 : 11
x = -0.002