The 4th and the last terms of an A.P. are 11 and 89 respectively. If there are 30 terms in the
A.P., find the A.P. and its 23rd term
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Answer:
A4 = 11 =>( a + 3d) = 11=> a = 11-3d .....eq1
Last term = 89
N=30
An= 89
Therefore: An = a + (n-1)d
89= 11-3d + (30-1)d
89 = 11-3d + 29 d
89 = 11 + 26d
89-11 =26 d
78/26 = d
D = 3
a = 11-3d
a = 11 - 3(3)
a = 2
Therefore the AP is 2,5,8...
23rd term = a + 22d
= 2 + 22(3)
= 2 + 78
23rd term = 80
.
Step-by-step explanation:
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