Which term of the AP : 3 , -2 , -7 , -12 ...... Will be -77 ? Find the sum of this A.P up to the term -77? T
Answers
Answered by
1
17th term will be the -77
mukku44:
And the sum is 14476
Answered by
8
a1=3
a2=-2
a3=-7
(common difference)d=a2-a1
◆d=-2-3=-5◆
Use formula
an=a+(n-1)d
-77=3+(n-1)(-5)
-80=(n-1)(-5)
n-1=16
n=17
◆17th term of this A.P. is -77◆
Sn=n/2[2a+(n-1)d]
Sn=17/2[2×3+(17-1)(-5)
Sn=17/2[6+(-80)]
Sn=17×(-37).
Sn=-629.
a2=-2
a3=-7
(common difference)d=a2-a1
◆d=-2-3=-5◆
Use formula
an=a+(n-1)d
-77=3+(n-1)(-5)
-80=(n-1)(-5)
n-1=16
n=17
◆17th term of this A.P. is -77◆
Sn=n/2[2a+(n-1)d]
Sn=17/2[2×3+(17-1)(-5)
Sn=17/2[6+(-80)]
Sn=17×(-37).
Sn=-629.
Similar questions