Question

1+3+5+7.....…...+99=​

Answer 1

Answer:

2500

Step-by-step explanation:

a = 1

d = 2

an or L = 99

using An formula

${a}_{n} =a + (n - 1)d \\ \\ 99 = 1 + (n - 1)2 \\ \\ 98 = (n - 1)2 \\ \\ \frac{98}{2} = n - 1 \\ \\ n = 50$

Using Sn formula

${s}_{n} = \frac{n}{2} (a + l) \\ \\ {s}_{n} = \frac{50}{2} (1 + 99) \\ \\ {s}_{n} =25(100) \\ \\ {s}_{n} =2500$

Answer 2

Answer:

1,457

Step-by-step explanation:

1+3+5+7+ 9, 15, 21, 25, 27, 33, 35, 39, 45, 49, 51, 55, 57, 63, 65, 69, 75, 77, 81, 85, 87, 91, 93, 95, +99 = 1,457

hope it helps u

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