Question

the sum of n terms of an AP is 2n2+3n. the sum of its first 10 terms is​

Answer 1

$\bf \: S_{n} = 2n² + 3n$

Sum of first 10 terms , n = 10

$\bf \: S_{n} = 2(10)² + 3(10)$

$\bf \: \: \: \: \: \: = \: (2 \times 100) +( 3 \times 10)$

$\bf \: \: \: \: \: = 200 + 30$

$\bf \: \: \: \: \: = 230$

Answer 2

Step-by-step explanation:

S

n

=2n

2

+3n

We know that nth term of AP is given by

a

n

=S

n

−S

n−1

⟹a

n

=2n

2

+3n−2(n−1)

2

−3(n−1)

⟹a

n

=4n+1

Tenth term=a

10

=4×10+1

⟹a

10

=41