हल :- दिया गया है a3=15
मतलब, a+2d =15 ........(i)
तथा S10 =125
(10/2)[2a+(10-1)d]=125
5[2a+9d]=125
[2a+9d]=(125/5)
2a+9d=25 ...........(ii)
अब समीकरण (i) तथा (ii) से,
a+2d =15 ........(i) ×2
2a+9d=25 ...........(ii)×1
2a+4d =30 ........(iii)
2a+9d=25 ........(iv)
अब समीकरण (iii) में से (iv) को घटाने पर,हम पाते हैं कि
2a+4d-(2a+9d) =30-25
⇒2a+4d-2a-9d =5
⇒4d-9d=5
⇒-5d=5
⇒d=5/(-5)
या d =-1
फिर समीकरण (i) में d का मान रखने पर,हम पाते है कि
a+2×(-1) =15
a -2 =15
a=15+2
a=17
अतः a10=a+9d
=17+9(-1)
=17-9
=8
Class math exercise 5.3 Q.3(ii) in hindi⇒click here
Class math exercise 5.3 Q.3(iii) in hindi⇒click here
Class math exercise 5.3 Q.3(v) in hindi⇒click here
Class math exercise 5.3 Q.3(vi) in hindi⇒click here
Class math exercise 5.3 Q.3(vii) in hindi⇒click here
Class math exercise 5.3 Q.3(viii) in hindi⇒click here
class 10th math exercise 5.3 question 3(ix) in hindi- click here
