Question

Find the number of terms in AP, -2, 3, 8...........288. find their sum

Answer 1

a = -2

d= 3 - (-2) = 3 + 2 = 5

last term = 288

=>288 = -2 + (n-1)5

=>(n-1)5 = 230

=> n-1 = 46

=> n = 47

no of terms = 47

sum = 47/2 [-2+288]= 47[286/2]

= 47(143)=6721

hope it helps mark as brainliest

Answer 2

tn=288 ,a=-2,d=5

by formula.

tn =a+(n-1)d

288=-2+(n-1)×5

288+2=(n-1)×5

290÷5=(n-1)

58=(n-1)

n=58+1

n=59.