Which term of A.P. 72, 70, 68, 66, ... is 40?
(A) 16
(B) 17
(C) 18
(D) 20
Answers
Answered by
1
Answer:
17th
Step-by-step explanation:
a=72,d=70−72=68−70=66−68=−2
a
n
=40
General term : a
n
=a+(n−1)d
a+(n−1)d=40
72+(n−1)(−2)=40
72−2n+2=40
2n=34
n=17
Answered by
1
Answer:
d = 70-72 = -2
an = a + (n-1)d
40 = 72 + (n-1) -2
40-72 = (n-1)-2
-32 = (n-1)-2
-32/-2 = n-1
16 = n-1
n = 16+1 = 17
(b) 17
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