Answer:
[tex] S_{10} = 135[/tex]
Step-by-step explanation:
Given sequence is:
3 + 6 + 9 +...
Here,
a = 3, d = 6 - 3 = 3, n = 10
[tex]\because S_n = \frac{n}{2} \{2a + (n - 1)d \} \\ \\ \therefore \: S_{10} = \frac{10}{2} \{2 \times 3 + (10 - 1) \times 3\} \\ \\\therefore \: S_{10} = 5 \{6 + 7 \times 3\} \\ \\\therefore \: S_{10} = 5 \{6 + 21\} \\ \\\therefore \: S_{10} = 5 \times 27 \\ \\ \huge \orange{ \boxed{\therefore \: S_{10} = 135}} \\ \\[/tex]
