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x + x + 1 + x + 2 + .........+ x + 99 = 5450
100x + ( 1 + 2 + ..... + 99 ) = 5450
100x + 4950 = 5450
100x = 500
x = 5
vậy: x = 5
bạn tk mk nha! đúng 100%.
x + (x + 1) + (x + 2) + .... + (x + 99) = 5450
<=> x + x + 1 + x + 2 + .... + x + 99 = 5450
<=> ( x + x + ... + x ) + ( 1 + 2 + ... + 99 ) = 5450
<=> 100x + 99.100/2 = 5450
<=> 100x + 4950 = 5450
<=> 100x = 500
=> x = 5
Vậy x = 5
3 . ( 5x -1 ) - 2 = 70
3 . ( 5x -1 ) = 70 + 2
3 . ( 5x -1 ) = 72
5x -1 = 72 : 3
5x -1 = 24
5x = 24 + 1
5x = 25
5x = 52
=> x = 2
a, \(x+\left(x+1\right)+\left(x+2\right)+...+\left(x+90\right)=5450\)
\(\left(x+x+x+...+x\right)+\left(1+2+3+...+90\right)=5450\)
\(91x+4095=5450\)
\(91x=1355\)
\(x=\frac{1355}{91}\)
b, \(2^x+2^{x+1}+2^{x+2}=960-2^{x+3}\)
\(2^x+2^x.2+2^x.2^2+2^x.2^3=960\)
\(2^x\left(1+2+2^2+2^3\right)=960\)
\(2^x.15=960\)
\(2^x=64=2^6\)
\(\Rightarrow x=6\)
x+(x+1)+(x+2)+......+(x+99)=100x+99.100/2=100x+4550=5450
=>100x=900=>x=9. Vậy: x=9
\(b,2^x+2^{x+2}=960-2^{x+3}\Leftrightarrow2^x+2^{x+2}+2^{x+3}=960\)
\(\Leftrightarrow2^x\left(1+4+8\right)=960\Leftrightarrow2^x.13=960\Rightarrow2^x=960:13\Rightarrow\left(\text{có sai đề ko?}\right)\)
1A, x+(x+1)+(x+2)+...+(x+99)=5450
(x+x+x+x+...+x)+(1+2+3+4+...+99)=5450
x*100+4950=5450
x*100 =5450-4950
x*100 =500
x =500:100
x = 5
Vậy x = 5
Học tốt nha~
a: 43/52>26/52=1/2=60/120
b: 17/68=1/4<1/3=35/105<35/103
c: \(\dfrac{2018\cdot2019-1}{2018\cdot2019}=1-\dfrac{1}{2018\cdot2019}\)
\(\dfrac{2019\cdot2020-1}{2019\cdot2020}=1-\dfrac{1}{2019\cdot2020}\)
2018*2019<2019*2020
=>-1/2018*2019<-1/2019*2020
=>\(\dfrac{2018\cdot2019-1}{2018\cdot2019}< \dfrac{2019\cdot2020-1}{2019\cdot2020}\)
a) a = 2, b = 0.
b) a = 6, b = 0.
c) a = 5, b = 5.
d) a = 4, b = 0.
e) a = 1, b = 0.
f ) a = 2, b = 0.
g) a = 2, b = 0.
h) a = 2,5,8 , b = 0.
\(\dfrac{19}{19}\) = 1 < \(\dfrac{2005}{2004}\) vậy \(\dfrac{19}{19}\) < \(\dfrac{2005}{2004}\)
\(\dfrac{72}{73}\) = 1 - \(\dfrac{1}{73}\)
\(\dfrac{98}{99}\) = 1 - \(\dfrac{1}{99}\)
Vì \(\dfrac{1}{73}\) > \(\dfrac{1}{99}\) nên \(\dfrac{72}{73}\) < \(\dfrac{98}{99}\)
2225 = (23)75 = 875
3151 > 3150 = (32)75 = 975
=> 3151 > 975 > 875
=> 3151 > 2225
4n - 5 chia hết cho 2n - 1
=> 4n - 2 - 3 chia hết cho 2n - 1
=> 2.(2n - 1) - 3 chia hết cho 2n - 1
Do 2.(2n - 1) chia hết cho 2n - 1 => 3 chia hết cho 2n - 1
Mà n thuộc N => 2n - 1 > hoặc = -1
=> 2n - 1 thuộc {-1 ; 1 ; 3}
=> 2n thuộc {0 ; 2 ; 4}
=> n thuộc {0 ; 1 ; 2}