Question

1 st one plzz solve ...which term of sequence 17

Answer 1

tn =7-3n

first term = a=t1 = 7-3*1 = 7-3 = 4

t2 =7-3*2 = 7-6=1
t3 =7-3*3 = 7-9=-2

4,1,-2 ...are in Arithmetic progression

a= 4,
common difference =d= t2-t1 =1-4=-3
n=25

suu of 25 terms = sn =n/2[2a+(n-1)d]

s25 = 25/2[2*4+(25-1)(-3)]

= 25/2*[8-24*3]
=25/2 [8-72]
=25/2*(-64)
=-25*32
=-400