Question

what term of the A.P 4,1,-4,............ is -77

Answer 1

Answer:

Step-by-step explanation:

a = 4

d = -3

an = -77

n = ?

an = a + (n-1)d

-77 = 4 + (n-1)(-3)

-77 = 4+ 3 - 3n

-77 = 7 - 3n

-84 = -3n

n = 84/3

n = 28

Hence 28 term of AP is -77.

Answer 2

Answer:

The given A.P. is 4,1,-4....

First term (a) = 4

Difference (d) = 1-4 = -3

Let the nth term of the A.P. be -77

an = a+(n-1)d

-77 = 4+(n-1)(-3)

-77 - 4 = -3(n-1)

81/3 = n-1

21 = n-1 => 21+1 = n => n = 22

Hence, the number of terms of the given A.P. is 22.