passpadi

2008

Mathematics

JAMB

The fifth term of an A.P is 24 and the eleventh term is 96. Find the first term.

A.

12

B.

4

C.

-12

D.

-24

Correct Answer: -24

Explanation

U5 = 24, n = 5 and U11 = 96, n = 11 Un = a + (n-1)d 24 = a + (5-1)d imply 24 = a+4d .....eqn1 96 = a + (11-1)d imply 96 = a+10d ...eqn2 eqn1 - eqn2 -72 = -6d d = 72/6 = 12 but 24 = a+4d 24 = a + 4(12) 24 = a + 48 a = 24-48 a = -24

U5 = 24, n = 5 and U11 = 96, n = 11 Un = a + (n-1)d 24 = a + (5-1)d imply 24 = a+4d .....eqn1 96 = a + (11-1)d imply 96 = a+10d ...eqn2 eqn1 - eqn2 -72 = -6d d = 72/6 = 12 but 24 = a+4d 24 = a + 4(12) 24 = a + 48 a = 24-48 a = -24
passpadi
©2023 Passpadi. All rights reserved.