The sum of the first twelve terms of an Arithmetic Progression is 168. If the third term is 7, find the values of the common difference and the first term.

YoungJonathan

2 years ago

S12=12/2(2a+11d)
6(2a+11d)=168
2a+11d=28
2xa+2d=7
2a+11d=28
-2a+4d=14

7d=14
— —
7. 7
d=2

input d in a+2d
a+2(2)=7
a+4=7
a=3