các bn giúp mink nha
Trả lời:
\(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+...+\left(x+9\right)+\left(x+10\right)=240\)
\(\Leftrightarrow\left(x+x+x+...+x+x\right)+\left(1+2+3+...+9+10\right)=240\)
\(\Leftrightarrow10x+\left(10+1\right)\times\left[\left(10-1\right)\div1+1\right]\div2=240\)
\(\Leftrightarrow10x+11\times10\div2=240\)
\(\Leftrightarrow10x+55=240\)
\(\Leftrightarrow10x=185\)
\(\Leftrightarrow x=18,5\)
Vậy \(x=18,5\)
( x+1 )+( x+2 )+...+( x+10 ) = 240
= x+1 + x+2 + x+3 +...+ x+9 + x+10 = 240
= ( x+x+x+...+x ) + ( 1+2+3+...+9+10 ) = 240
= 10.x + 55 = 240
10.x = 240-55
10.x = 185
x = 185 : 10
x = 18,5
( x+1 ) + ( x+2 ) + ( x+3 ) + ...........( x+9 ) + ( x+10 ) = 240
( x + x + ... + x) + ( 1 + 2 + .. + 10 ) = 240
10 x + 10.( 10 + 1 ) : 2 = 240
10 x + 55 = 240
10 x = 185
x = 185 : 10 = 37/2
Ta có: \(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+...+\left(x+9\right)+\left(x+10\right)=10x+55\)
\(10x+55=240\Rightarrow10x=185\Rightarrow x=\frac{37}{2}\)
( x+1 ) + ( x+2 ) + ( x+3 ) + ...........( x+9 ) + ( x+10 ) = 240
240 = X x 10 + [1+2+3+...+9+10]
240 = X x 10 + 55
240-55 = X x 10
185 = X x 10
185: 10 = X
1,85 = X
