Question

if a6=-10 and a10=-26 in A.P find a15​

Answer 1

Answer: -46

Step-by-step explanation: first of all let's find the value of "d"

a10-a6 = difference of 4 terms

& a10= -26, a6 =-10

The difference of 4 terms = (-26) - (-10)

Which is -16

So as the difference is 4 terms we shall divide -16 by 4 to get difference of 1 term

Which is -4

So "d" = -4

So now let's find first term "a"

As per formula, tn = a+(n-1) d

t6 = a+(6-1) -4 ( t6 = a6)

-10 = a(5) -4

-10 = a(-20)

a = 10

Now a15 = t15

t15 = a+(n-1) d

t15 = a+(15-1) d

t15 = 10+ (14) -4

t15 = 10 + (-56)

t15 = -46