Question

26. Prove that Sx =
| 2a + (x - 1)]​

Answer 1

Step-by-step explanation:

let first term be a.

common difference be d.

so AP will be

a,a+d,a+2d,a+3d....

now Sx i.e sum to x terms will be

Sx=x/2(a+ax)

ax=a+(x-1)d

so Sx=x/2(a+a+(x-1)d)

Sx=x/2(2a+(x-1)d)