Question

In a ap the first term is a second term is b and last term is l then find the sumation of the ap​

Answer 1

Step-by-step explanation:

GIVEN : IN AN AP ,

First term = a

Second term = b

Last term = l

TO FIND : SUM OF ALL TERMS

SOLUTION : as d = b - a

As nth term of AP is given by

an = a + (n-1)d

l = a + (n-1)b-a

n = l+b -2a / b-a ----- (1)

Now sum of n terms is given by

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

l+b-2a /2(b-a)[2a+ (l+b-2a /b-a-1)b-a ] =

l+ b -2a /2(b-a) +l+a

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