Question

Prove that the following :

Answer 1

Step-by-step explanation:

since,. l= a+(n-1)d -(eqn 1)

Sn = n/2[2a +(n-1)d]

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

from eqn 1,

Sn =n/2[a + l]

proved