Please done this by proper formula
Chapter= A.P
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1). a=19 ; d=18×5+1/5-19
=91-95/5
= -4/5
therefore according to question;
a+(n-1)d<0
19+(n-1)(-4/5)<0
19-4/5n+4/5<0
99/5-4/5n<0
-4/5n<-99/5
-4n<-99
n>-99/-4
n>24.75
therefore n must be more than 24.75 to have negative term
therefore first negative term i.e;n=25
that is option d)25
2) a=5;d=13-5=8 an=181
an=a+(n-1)d
181=5+(n-1)8
176/8=n-1
22+1=n
n=23
therefore option b)23 is correct
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