Question

2. In an AP if a = -7.2. d = 3.6. an = 72. then n is
(a) 1 (b) 3 (c) 4(d)​

Answer 1

Step-by-step explanation:

a= -7.2 d=3.6 an= 72

we know,

An= a + (n-1)d

substituting the values

72= -7.2 +(n-1)3.6

72 = -7.2 + 3.6n -3.6

72= -10.8+3.6n

82.8=3.6n

n=82.8/3.6

n= 23