Question

find 11th and 15th term of the arithmetic progression:- -3, -1/2, 2....​

Answer 1

Answer:

In a.p 11th term = a+10d, where a is the first term and d is the common difference, Here a=-3 and d= -1/2+3= 5/2, 11th term = a+10d= -3+10(5/2) = -3+25= 22, 15th term = a+14d= -3+14(5/2)= -3+35= 32. Hence the 11th term and 15th term of the a.p are respectively 22, 32. Hope this helps you

Answer 2

★ $\large{\sf{\underline{Given:-}}}$

→ $a_{1} = - 3$

→ $d = - \frac{1}{2} + 3 = \frac{5}{2} = 2.5$

★ $\large{\sf{\underline{To\:find:-}}}$

• 11th term = ?
• 15th term = ?

★ $\large{\sf{\underline{Explanation:-}}}$

★ We know that:-

→ 11th term = a + 10d → (1)

→ 15th term = a + 14d → (2)

★ Now, taking eqn (1)

→ $a_{11} = a + 10d$

→ $a_{11} = -3 + 10 \times 2.5$

→ $a_{11} = -3 + 25$

→ ${\boxed{\sf{ a_{11} = 22}}}$

★ Now, taking eqn (2)

→ $a_{15} = a + 14d$

→ $a_{15} = -3 + 14 \times 2.5$

→ $a_{15} = -3 + 35$

→ ${\boxed{\sf{a_{15} = 32}}}$

Therefore, the 11th term of the A.P is 22 and the 15th term of the A.P is 32.

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