Tim x
1+5+9+13+17+.....+x=501501
1+5+9+13+17+...+x = 501501
tim x
nhanh nhe mn, sang mai minh can roi
ai nhanh tick
Ta có 5=2+3; 9=4+5: 13=6+7: 17=8+9......
Do vậy x=a + ( a+1 ) ( a thuộc N )
Nên 1+5+9+13+16.....+x=1+2+3+4+5+6+7.....+a+(a+1)=501501
Hay (a+1)(a+2)=1003002=1001.1002
==>a=1000
do đó x=1000+(1000+1)=2001
tim x biet :1+5+9+13+16+...+x=501501
(x+1)x:2=501.1001. =>(x+1)x=1002.1001=>x=1001
Ta co :
x+1:4+1=501501
x+1:4 = 501501-1
x+1:4 =501500
x+1 = 501500:4
x+1 = 125375
x = 125375 -1
x =125374
Vay x=125735
**** nhe
Tim x:
1+5+9+13+.....+x=501501
\(1+5+9+...+x=501501\)
\(\Leftrightarrow\frac{\left(1+x\right).\left[\left(x-1\right)\div4+1\right]}{2}=501501\)
\(\Leftrightarrow\left(1+x\right).\left[\left(x-1\right)\div4+1\right]=501501.2\)
\(\Leftrightarrow\left(1+x\right).\left[\frac{x-1}{4}+1\right]=1003002\)
\(\Leftrightarrow\frac{x-1}{4}\left(1+x\right)+x+1=1003002\)
\(\Leftrightarrow\frac{x-1}{4}+\frac{x-1}{4}x+x=1003001\)
\(\Leftrightarrow\frac{x-1+x\left(x-1\right)+4x}{4}=1003001\)
Tự giải tiếp
1+5+9+13+17+..............+ x = 501501
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1+5+9+13+17+...+x=501501
1+5+9+13+17+...+x=50151
ta có 1=0+1
5=2+3
9=4+5
13=6+7
17=8+9
.................
=>x= a+(a+1)
nên 1+5+9+...+x=501501
(=)0+1+2+3+4+5+....+a+(a+1)=501501
(=) [(a+1).9a+1+10]:2=501501
(=)(a+1).(a+2)1003002-1001.1002
=>a=1000
=>x=2001
tìm x biết 1+5+9+13+17+...+x =501501
Ta có: 5 = 2+3; 9 = 4+5 ; 13 = 6+7 ; 17 = 8+9;.....
Do vậy x = a + ( a + 1) ( a thuộc N )
Nên 1 + 5 + 9 + 13 + 16 + ....+ x = 1+2+3+4+5+6+7+.....+a+ ( a + 1 ) = 501501
Hay (a + 1)( a + 2) = 1003002 = 1001 . 1002
Suy ra : a = 1000
Do đó : x = 1000 + ( 1000+ 1) = 2001
Vậy, x= 2001
Ta có: \(\left(x+1\right).x\div2=501501\)
\(\left(x+1\right).x=501501.2\)
\(\left(x+1\right).x=10003002\)
\(\left(x+1\right).x=10003002=\)
tìm x biết 1+5+9+13+17+...+x =501501
Ta có: 5 = 2+3; 9 = 4+5 ; 13 = 6+7 ; 17 = 8+9;.....
Do vậy x = a + ( a + 1) ( a thuộc N )
Nên 1 + 5 + 9 + 13 + 16 + ....+ x = 1+2+3+4+5+6+7+.....+a+ ( a + 1 ) = 501501
Hay (a + 1)( a + 2) = 1003002 = 1001 . 1002
Suy ra : a = 1000
Do đó : x = 1000 + ( 1000+ 1) = 2001
Tìm x : 1 + 5 + 9 + 13 + 17 +...+ x = 501501
TA có : 5 = 2 + 3 ; 9 = 4 + 5 ; 13 = 6 + 7 ; 17 = 8 + 9 ; ....
Do vậy x = a + ( a + 1 ) a thuộc N
Nên 1 + 5 + 9 + 13 + 17 + ..+ x = 1+ 2 + 3 + 4 +5 + 6 + 7 +...+ a +( a+ 1 ) = 501501
Hay ( a + 1 )(a + 2 ) = 1003002 = 1001.1002
Do đó x = 1000 ( 1000 + 1 ) = 2001
TÌM X
1+5+9+13+17+....+X= 501501