Question

tính tổng;

a,s=1+2+3+4+....+100

b,s=1+2+3+....+n

c,a=1+3+5+....+99

d,b=2+4+6+....+100

e,c=1+3+5+...+[2n+1][n thuộc n^*]

f,d=2+4+6+...+2n

giúp tôi với

 

Answer 1

a=5000

Answer 2

1 + 2 + 3 + ... + 100

= (100 + 1).100 : 2

= 101.50

= 5050

Answer 3

a) \(S=1+2+3+4+...+100\)

\(S=\frac{\left(100+1\right)\left[\left(100-1\right):1+1\right]}{2}\)

\(S=5050\)

b) \(S=1+2+3+...+n\)

\(S=\frac{\left(n+1\right)\left[\left(n-1\right):1+1\right]}{2}\)

c) \(A=1+3+5+...+99\)

\(A=\frac{\left(99+1\right)\left[\left(99-1\right):2+1\right]}{2}\)

\(A=2500\)