we begunu u
- find the number of terms of the AP: 54,51,48.... So that their
Sum is 513
...otodes of 8
Answers
Answered by
0
Answer:
Number of terms = 54,51,48,45,42,39,36,33,30,27,24,21,18,15,12,9,6,3, 0
Sum = 54+54+54+54+54+54+5+35
=413
Hope this will help you
THANK you
Please mark me BRAINLIST
Answered by
0
a=54
d=(-3)
S^n=513
now, using of S^n formula
S^n = n/2{2a+(n-1)d}
513=n/2{2*54+(n-1)-3}
513=n/2{108+(-3n+3)}
513=n/2{108-3n-3}
513*2=n(105-3n)
1026=105n-3n^2
3n^2-105n+1026=0
3(n^2-35n+342)=0
n^2-35n+342=0
n^2-19n-18n+342=0
n(n-19)-18(n-19)=0
(n-18)(n-19)=0
therefore no. of terms be 18 or 19
Similar questions