Question

find the sum of last 10 terms of an ap 8 10 12...126​

Answer 1

Given AP,

8, 10, 12....... 126

Here,

• a = 8
• d = 10 - 8 = 2

On reversing the AP,

126, 124....... 8

Here,

• a = 126
• d = -2

we need to find the sum of first 10 terms,

S = n/2{(2a + (n - 1)d}

s10 = 10/2 { 2(126) + (10-1)-2 }

= 5{252 + 9(-2)

= 5{252 - 18}

= 5{234}

= 1270

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Answer 2

Refer to this attachment