JAMB - Mathematics (2012 - No. 17)
The nth term of a sequence is n2 - 6n - 4. Find the sum of the 3rd and 4th terms.
24
23
-24
-25
Explicació
n2 - 6n - 4
For the 3rd term,
32 - 6(3) - 4
9 - 18 -4 = -13
For the 4th term,
42 - 6(4) - 4
16 - 24 - 4 = -12
Sum of both terms
-13 - 12 = -25
For the 3rd term,
32 - 6(3) - 4
9 - 18 -4 = -13
For the 4th term,
42 - 6(4) - 4
16 - 24 - 4 = -12
Sum of both terms
-13 - 12 = -25