JAMB - Mathematics (1994 - No. 17)
If the 6th term of an arithmetic progression is 11 and the first term is 1, find the common difference.
\(\frac{12}{5}\)
\(\frac{5}{3}\)
-2
2
คำอธิบาย
In an AP, Tn = a + (n - 1)d
T6 = a + 5d = 11
The first term = a = 1
∴ T6 = 1 + 5d = 11
5d = 11 - 1
5d = 10
∴ d = 2
T6 = a + 5d = 11
The first term = a = 1
∴ T6 = 1 + 5d = 11
5d = 11 - 1
5d = 10
∴ d = 2