Which term of an Ap 19, 18 1/5 and 17 2/5 is the first term
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we must find a common defference of A.p.
common difference (d) = first term - second term
=18 1/5-19
91/5-95/5
-4/5
hence,
the common difference is -4/5 or-0.8
now to estimate which term of this of THIS A.P. will be negative let us
assume
the nth terms of A.p. is 0.
formula for the nth term of an A.P. is =a+(n-1)d
then
0=19+(n-1)x-0.8
0=19-0.8n+0.8
0.8n=19.8
19.8/0.8
n=24.75
a.p. will be negative
let us make sure , just in those case
19+(25-1)×-0.8
19+(24×-0.8)
19+(-19.2)
19-19.2
-0.2
answer is 25
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