Question

the 6th term of an ap is -10 and the 10th term is minus 20 determine the 15th term of AP​

Answer 1

Step-by-step explanation:

t6 = (-10)

a + 5d = -10.......(1)

t10 = (-20)

a + 9d = -20.......(2)

solving (1)&(2)=>

4d = -10

d = -10/4

put d = -10/4 in (1)

a + 5(-10/4)= -10

a - 50/4 = -10

a = -10 + 50/4

a = 10/4

t15 = a + 14d

= 10/4 + 14×(-10/4)

= 10/4 - 35

= -130 /4

= 32.5 ~ 33