JAMB - Mathematics (2001 - No. 12)
The sixth term of an A.P is half of its twelfth term. The first term of the A.P is equal to
zero
half of the common difference
double the common difference
the common difference
คำอธิบาย
1st statement: U6 = 1/2(U12)
a + (n -1)d = 1/2[a + (n-1)d]
a + 5d = a + 11d
2(a + 5d) = a + 11d
2a + 10d = a + 11d
Solving, => a = d
Hence the first term is equal to the common difference
a + (n -1)d = 1/2[a + (n-1)d]
a + 5d = a + 11d
2(a + 5d) = a + 11d
2a + 10d = a + 11d
Solving, => a = d
Hence the first term is equal to the common difference