given a3=15,S10 = 125, find d and a10
Answers
Answered by
2
Step-by-step explanation:
11th
Maths
Sequences and Series
Arithmetic Progression
In an AP, given a3 = 15, S1...
MATHS
In an AP, given a
3
=15,S
10
=125, find d and a
10
.
EASY
Share
Study later
ANSWER
a
3
=15,s
10
=125
a
3
=a+(3−1)d
15=a+2d
a=15−2d
s
10
=
2
10
[2a+(10−1)d]
125=5[2a+9d]
25=2a+9d
25=2(15−2d)+9d
25=30−4d+9d
5d=−5
d=−1
a=15−2×(−1)
a=17
a
10
=a+(10−1)(−1)
a
10
=17−9
a
10
=26
Similar questions