(=)10x+(1+2+....10)=165
(=)10x+55=165
(=)10x=110
(=)x=11
(X + 1) + (X + 2) + (X + 3) + ..... + (X + 10) = 165
( X x 10 ) + ( 1 + 2 + 4 + ... + 10 ) = 165
( X x 10 ) + 45 = 165
X x 10 = 165 - 45
X x 10 = 120
X = 120 : 10
X = 12
Ta có \(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+...+\left(x+10\right)=165\)
\(\Rightarrow\left(x+x+x+...+x\right)+\left(1+2+3+...+10\right)=165\)
\(\Rightarrow10x+55=165\)
\(\Rightarrow10x=110\)
\(\Rightarrow x=11\)
(X + 1) + (X + 2) + (X + 3) + ..... + (X + 10) = 165
( X * 10 ) + ( 1 + 2 + .... + 10 ) = 165
X *10 + 45 = 165
X * 10 = 165 - 45
X * 10 = 120
X = 120 : 10
X = 12
(X + 1) + (X + 2) + (X + 3) + ..... + (X + 10) = 165
x+1+x+2+x+3+x+4+x+5+.............+x+10=165
10x + (1+9) +(2+8)+(3+7)+(4+6)+(5+10)=165
10x+55=165
10x=165-55
10x=110
x=11
vậy x=11
(X + 1) + (X + 2) + (X + 3) + ..... + (X + 10) = 165
(X+X+X...+X) + (1+2+3+...+10) =165 (có 10-1+1=10 số hạng x)
10. x + 45 = 165
10x =165-45
10x = 120
x = 120 : 10 = 12
Sorry mn
mk viết nhầm x = 11 ( còn cách làm như vậy nha )
\(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+...+\left(x+10\right)=165\)
\(\left[x+x+x+...+x\right]+\left[1+2+3+...+10\right]=165\)
\(\left[10x\right]+\left[\left(1+10\right).10:2\right]=165\)
\(\left[10x\right]+\left[11.10:2\right]=165\)
\(10x+55=165\)
\(10x=110\)
\(x=110:10\)
\(x=11\)
(x + 1) + (x + 2) + ..... + (x + 10) = 165
( x . 10 ) + ( 1 + 2 + 4 + ... + 10 ) = 165
(x . 10 ) + 45 = 165
x . 10 = 165 - 45
x . 10 = 120
x = 120 : 10
x = 12
Tìm x :
( X + 1) + ( X + 2 ) + ( X + 3 ) + ... + ( X + 10 ) = 165
Số số hạng của dãy là : ( 10 - 1 ) : 1 + 1 = 10 ( số hạng )
( X + X + X + ... + X ) + ( 1 + 2 + 3 + .... + 10 ) = 165
X × 10 + [ ( 10 + 1 ) × 10 : 2 ] = 165
X × 10 + 55 = 165
X × 10 = 165 - 55
X × 10 = 110
X = 110 : 10
X = 11
Vậy X = 11