Question

In An arithematic sequence the sum of 5th term and 16th in 67.
find The sum of first and 20th term??​

Answer 1

I hope understood this.

Answer 2

Answer:

Step-by-step explanation:

To find out

a.X1 +X20=X2+X19........=X5+X16=67

b.X10+X11=67

X11=67-32

=35

solution

c. d=35-32=3

f+9d=32

f=32-(9×3)

=5

Xn=3n+2

Sn= n/2(5+3n+2)

= n/2(3n+7)

= ((3n^2)/2)+(7n/2)

=(1.5)^2+(3.5)n

hope it helps

:)