Question

Find the 11th term from the last term (towards the first term) of an AP 12, 8,4, ..., -84​

Answer 1

$a = 12 \\ d = 8 - 12 = - 4 \\ tn = a + d(n - 1) \\ - 84 = 12 - 4(n - 1) \\ - 84 - 12 = - 4(n - 1) \\ \frac{ - 96}{ - 4} + 1 = n \\ n = 25 \\ \\ term \: from \: end \: = n - r + 1 \: term \: from \: start \\ = 25 - 11 + 1 \\ = 15th \: term \: from \: start\\ \\ t15 = a + 14d \\ = 12 +( - 4 \times1 4) \\ t15 = - 44$

PLZ MARK AS BRAINLIEST.

Answer 2

Step-by-step explanation:

a=12

d= -4

an= -84

an=a+(n-1)d

-84=12+(n-1)× -4

-84=12+[(-4n) + 4]

-84 -12= -4n +4

-96= -4n+4

-96-4= -4n

-100 = -4n

-100/-4= n

n=25

So, 25 terms are there in total!

now, finding 11th term from 25th Term↓

→11thTerm=(25thterm-10 terms)

→15th term

=>a15=10+(15-1)×-3

a15=10+(14×-3)

a15=10+-42

a15= -32

Means,The 11th Term from the Last term is -32