Answer:
S₁₀ = 270
Step-by-step explanation:
The sum to n terms of an arithmetic sequence is
• [tex]S_{n}[/tex] = [tex]\frac{n}{2}[/tex] [ 2a₁ + (n - 1)d ]
a₁ is the first term, d the common difference, n the term position
here a₁ = 9 , d = a₂ - a₁ = 13 - 9 = 4 , n = 10 , then
S₁₀ = [tex]\frac{10}{2}[/tex] [ (2 × 9) + (9 × 4) ]
= 5(18 + 36)
= 5 × 54
= 270
Answer:
270
Step-by-step explanation:
9,13,17,21,....
in this AP
d(common difference)=13-9=17-13=...
d=4
a(first term)=9
n(no.of terms)=10
we know that,
Sn=n/2(2a + (n-1)d)
S10 = 10/2(2×9 + (10-1)4)
=5(18+36)
= 5(54)
=270
so sum of first 10 terms of the AP 9, 13 , 17, 21....
is 270