Question

IF THE MIDDLE TERM OF FINITE AP WITH 7 TERMS IS 21 FIND THE SUM OF ALL THE TERMS OF AP​

Answer 1

Answer:

SOLUTION

GIVEN

The middle term of a finite AP with 7 terms is 21

TO DETERMINE

The sum of all terms of the AP

EVALUATION

Let first term = a and common difference = d

Number of terms = n = 7

∴ Middle term

= 4 th term

= a + ( 4 - 1 ) d

= a + 3d

So by the given condition,

See the figure☝︎

Hope its help you❀