Question

find x know :

10 + 11 + 12 + 13 + 14 + . . . + x = 5106

quik reply

Answer 1

We have: 

 10 +  11 + 12 + ... + x  = 5106

\(\frac{\left(x-10\right)\left(x+10\right)}{2}=5106\)( x-10 is the number of classes ; x+10 is overall a pair)

(x-10)(x+10)=10212

We can't find x because x isn't natural number !

Answer 2

Ta có: \(10+11+12+...+x=5106\)

\(\Leftrightarrow\frac{\left(x+1\right).x}{2}=5106\)

\(\Leftrightarrow x\left(x+1\right)=10212\)

Mà 10212 ko phân tách ra đc thành tích của 2 stn liên tiếp

=> ko tìm đc x