Question

Find sum of first 12 terms of an AP whose first term is 10 and 5th term is 2

Answer 1

Answer:

sum=-12

Step-by-step explanation:

explained in picture

Answer 2

Answer:

-12

Step-by-step explanation:

First term =a = 10

5th term= a5= 2

2=10+(5-1)d

2=10+4d

-8 =4d

d = - 2

Sum of 12 terms=

n/2(2a+(n-1)d)

12/2(20+11×-2)

6(-2)

=-12

-12 is the sum