Question

which term of the A.P. -1,3,7,11....is 99?​

Answer 1

Answer:

an =a+(n-1)d

99=1+(n-1)2

99-1=(n-1)2

98/2=(n-1)

49=(n-1)

n=50

Answer 2

Here:

First term (a1) = -1

Common Difference (d) = 4

an = a + (n-1)d

99 = 1 + (n-1)(4)

99 - 1 = (n-1)(4)

100/4 = n-1

25 = n-1

25+1 = n

26 = n

So, 26th term is 99.