Question

If the sum of first n even natural number is
240. find the value of n.​

Answer 1

Answer:

a=2 , d=2, sn= 420

sn= n/2[4+2n-2]

840=n[2+2n]

2n ka squar + 2n = 840

2( n ka squar + n)

n ka squar + n = 420

n ka squar+ ho 420=0

.......................

n = -b + √b ka squar - 4ac/2a

n=-1 +√1 -4×1×-420=2

-1+√1681/2

1+41-2

-1+41/2

=40/2

=20

sry yaar mujhe laga ki question ke last mai 420 hai isliye 420 prr hi bna diye hai sry if u can understand then okk and if u r not able to understand then tell me i will answer on 240 again