Question

1+2+3+4+...... find nth sum​

Answer 1

Answer:

n(n+1)/2

Eg: 1+2+3+4=10

Here n=4

4(4+1)/2=4×5/2=20/2=10

Answer 2

Answer:

Step-by-step explanation:

S=n/2{2a+(n-1)d}

Here n=no of terms,

a=first term ,d=common difference

S=n/2{(2×1)+(n-1)×1}

S=n/2{2+(n-1)}

S=n/2{2+n-1}

S=n/2(n+1)

Sum to n terms