Question

(i) If for an A.P.-4. then 130 - tis ? (A) - 15 (B) 15 (0) 20 (D) - 20​

Answer 1

A N S W E R :

To find : T₂0 - T15.

T20 = a + (20 - 1)d.

→ T₂0 = a + 19d.

T15 = a + (15 - 1)d.

→ T15 = a + 14d.

→

(a + 19d) - (a + 14d).

a + 19d - a - 14d.

→ 19d - 14d.

5d = 5 x (-4)= - 20.

T20 - T15 = - 20.