Question

1+2+3+4+....+ x = 1275

tìm x

 

Answer 1

1+2+3+4+...+x=1275

[(x-1):1+1].(1+x):2=1275

x.(x+1)=1275.2

x.(x+1)=2550

x.(x+1)=50.51

x.(x+1)=50.(50+1)

=> x=50

chúc bạn học tốt nha

ủng hộ mk với nha

Answer 2

\(1+2+3+4+...+x=1275\)

\(\Rightarrow\frac{\left[\left(x-1\right):1+1\right].\left(x+1\right)}{2}=1275\)

\(\Rightarrow\frac{x\left(x+1\right)}{2}=1275\)

\(\Rightarrow x\left(x+1\right)=1275\times2=2550=50\times51\)

Vậy x = 50

Answer 3

\(1+2+3+4+.......+x=1275\)

<=>\(\left(x+1\right).\text{[}\left(x-1\right):1+1\text{]}\)

<=>                                                          \(=1275\)

                             \(2\)

<=>\(\left(x+1\right).\text{[}\left(x-1\right)+1\text{]}=2550\)

<=> \(\left(x+1\right).x=2550\text{ }\)

<=>\(\left(x+1\right).x=51.50\)

<=> \(x=50\)vậy \(x=50\)

Answer 4

x= 50 nhé=))))))))))))