Question

In an ap 5 times of the fifth term is equal to seven times of the seventh term prove that 12 term is zero

Answer 1

here is your answer. just take the value of 'a' and put it in A12.

Answer 2

Given, 5T5= 7T7
=>5(a + 4d)= 7(a + 6d)
=>5a + 20d= 7a + 42d
=>-2a= 22d
=>a= -11d

T12= a + 11d= -11d + 11d= 0