Question

If an =3+4n find the sum
of first 5 terms.​

Answer 1

Answer:

75

Step-by-step explanation:

an= 3 + 4n

a= 3 + 4 = 7

sum of first 5 terms = 5( a + a5)/2

a5 = 3 + 4(5)

=23

sum of first 5 terms = 5(7+23)/2

= 5 × ( 30)/2

= 5 × 15 = 75