Question

If the third and the ninth terms of an AP are 4 and -8 respectively, which term of this AP is zero?

a)5th
b)4th
c)3rd
d)2nd​

Answer 1

Answer:

5 th term

Step-by-step explanation:

Given,

a3=4 and a9=-8

a+2d=4 and a+8d=-8

solving both equations we get d=-2 a=8.

0=a+(n-1)d

0=8+(n-1)-2

0=8+2-2n

0=10-2n

2n=10

n=5

therefore 0 is fifth term of A.P..

THANK YOU!!!!!

Answer 2

Given:

• a+2d = 4
• a+8d = -8

To Find:

• a+4d
• a+3d
• a+2d
• a+d

Solution:

a+2d = 4. --(given) --(1)

a+8d = -8 --(given)--(2)

now , subtracting 1 from 2

a + 2d = 4

-a -8d = 8

---------------

-6d = 12

---------------

d = 12/-6

$\longrightarrow$$\sf\pink{ d = -2}$

putting value of d in eq. (1)

a +2(-2) =4

a -4 = 4

$\implies$$\sf\pink{a = 8}$

a) a + 4d

8+4(-2)

8-8

=0

$\sf {\boxed {\pink { a+4d = 0 }}}$

b)a+3d

8+3(-2)

8-6

=2

$\sf {\boxed {\pink { a+3d = 2}}}$

c) a+2d

= 4 ...(given)

$\sf {\boxed {\pink { a+2d = 4 }}}$

d)a+d

8+1(-2)

8-2

=6

$\sf {\boxed {\pink { a+3d = 6 }}}$