Question

the second of arithmetic sequence is 7. The sum of the first 4 terms of the arithmetic sequence is 12. Find the first term and the common difference

Answer 1

solve explanations:

let a be the first term and d be the common difference of the arithmetic sequence.
a + d = 7
a + (a + 3d) • 4 = 12
2
2a + 3d = 14
a + d = 7
a = 7 - d
2(7- d) + 3d = 14
14 - 2d + 3d = 14
d = 0
a + d = 7
a + 0 = 7
a = 7
The first term will be equal to 7 and the common difference is 0