Question

9 times the 9th term of an A.P. is equal to 11 times the 11th term , then its 20th term is

Answer 1

Answer:

0

Step-by-step explanation:

A9 = a+ 8d   - equation 1

A11 = a + 10d  -equation 2

9* A9 = 11* A11  -equation 3

9*(a+ 8d) = 11*(a + 10d)

9a +  72d = 11a + 110d  

-2a = 38d

a = -19d

A20 = a+ 19d

A20 = -19d + 19d

A20 =0

Answer 2

Answer: the real Question is this ...

If 9 times of 9th term of an AP is equal to  11 times of its 11th term  then find 20 times its 20th term

A9 = a+ 8d   - equation 1

A11 = a + 10d  -equation 2

9* A9 = 11* A11  -equation 3

9*(a+ 8d) = 11*(a + 10d)

9a +  72d = 11a + 110d  

-2a = 38d

a = -19d

A20 = a+ 19d

A20 = -19d + 19d

A20 =0