Question

if 6th term of an ap is -10 and its 10th term is -26 then find the 15th term of the ap.​

Answer 1

Answer:

$\huge{\red{\boxed{\boxed{\green{\sf{a15=-46}}}}}}$

Step-by-step explanation:

$\huge{\red{\boxed{\boxed{\green{\underline{\red{\sf{SOLUTION-}}}}}}}}$

□a6= -10

□a10= -26

To find:

○a15=?

$a6 = - 10 \\ = )a + 5d = -10 - - - - - (1) \\ \\ a10 = - 26 \\ = )a + 9d = - 26 - - - - - (2) \\ \\ on \: subtracting \: (1) \: from \: (2) \: we \: get \\ = ) a + 9d - (a + 5d) = - 26 - ( - 10) \\ = )a + 9d - a - 5d = - 26 + 10 \\ = )4d = - 16 \\ = )d = \frac{ - 16}{4} \\ = )d = - 4 \\ \\ putting \: value \: of \: d \: in \: (1) \\ = ) a + 5d = - 10 \\ = ) a + 5 \times - 4 = - 10 \\ = )a - 20 = - 10 \\ = )a = - 10 + 20 \\ = )a = 10\\ \\ a15 = a + 14d \\ = )10 + 14 \times - 4 \\ = )10 +( - 56) \\ = )10 - 56 \\ = ) - 46$

$\huge{\red{\boxed{\boxed{\green{\sf{a15=-46}}}}}}$

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