Question

solve: 1+5+9+.....+x=1770​

Answer 1

Step-by-step explanation:

an=a+(n-1)d

X=1+(n-1)4

=1+4n-4

X =4n-3

Sn=n/2(a+an)

1770=n/2(1+4n-3)

1770x2=n(4n-2)

3540=4n^2-2n

4n^2-2n-3540=0

-2 2n^2-n-1770=0

Sum=-1

Product =-1770x2=-3540

The numbers are = -60, 59

(2n^2-60n)(+59n-1770)

2n(n-30)+59(n-30)

n-30=0 or 2n+59=0

n=30 or n= -59/2

ANSWER

n can't be negative .so n=30

Sub n=30 in x=4n-3

X=4*30-3

=120-3

X=117

Answer 2

Step-by-step explanation:

what's find here please write properly....

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