Question

If five times the 5 term of an A.p is equal to eight times its 8 term then show that it's 13 term is zero

Answer 1

Answer:5 * a+4d= 8* a+ 7d

-36d = 3a  

yhen divide both side 3

we get

-12d = a

o =a + 12 d

a +12d = to 13 term

hence proved

Step-by-step explanation:

Answer 2

Answer:

Step-by-step explanation:

Let of the AP

first term= a

common difference=d

ATQ

5[a+(5-1)d]=8[a+(8-1)d]

5(a+4d)=8(a+7d)

5a + 20d = 8a + 56d

3a = 36d

a= -12d

Now 13th term

a+(13-1)d

=-12d+12d

=0