Question

.
The sum of r terms of an AP is 2r^2+3r.The nth term is
a. 2n- 1
b. 4n+1
c. 3n-1
d. 3n+ 1​

Answer 1

Answer:

6r−1

Step-by-step explanation:

MATHS

ANSWER

⇒S

1

=2(1)+3(1)

2

=5

S

n

=

2

n

{2a+(n−1)d}

S

n

=

2

n

{a+a+(n−1)d}

S

n

=

2

n

{a+a

n

}

2n+3n

2

=

2

n

{5+a

n

}

4+6n=5+a

n

⇒a

n

=6n−1

⇒a

r

=6r−1