Question

Find the 60th term of AP 8, 10, 12... if it has a total term of 60 terms. Hence find the sum of its last 10 terms.
plzz solve it
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Answer 1

AP = 8,10,12,......

n=60, a= 8,d= 2

an= a+(n-1)d

a60 = 8+(60-1)2

a60= 8+59×2aw

a60= 8+118 = 126

a60 = last term (l)

Sn=n/2[a+ l]

S60 = 60/2[8+126]

S60= 30×134 = 4020

a50 = 8+(50-1)2

a50= 8+49×2

a50=8+98 = 106

S50= 50/2[8+106]

S50= 25×114 = 2850

sum of last 10 terms = S60-S50

= 4020-2850 = 1170