Question

What is the sum of first term is an AP whose first term is 3 and sixth term is 27

Answer 1

Step-by-step explanation:

given question is not clear

but I give some ans

a1=3

a6=27

an=a+(n-1)d

27=3+5d

24/5=d

d=4.8

sum of n terms

sn=n/2 ×(a +an)

sn=n/2 ×(3+3+(n-1)4.8)

sn =n/2 ×(6+4.8n-4.8)

sn=1.2n+4.8n^2 /2

sn=0.6n+2.4n^2

sn=0.6(n+4n^2)

Answer 2

Step-by-step explanation:

$a = 3 \\ a_{n} = 27 \\ \\ S_{n} = \frac{n}{2} (a + a_{n}) \\ S_{n}= \frac{6}{2} (3 + 27) \\ S_{n} = 3(30) \\ S_{n} = 3 \times 30 \\ S_{n} = \underline{ \underline{90}}$