Question

Two ap have the same common difference. The first term of one of them is -1 and that of the other is -8. Then the difference between their 4th term is

Answer 1

✬ Difference = 7 ✬

Step-by-step explanation:

Given:

• Two AP have same common difference.
• First term of 1st AP is –1.
• First term of second AP is –8.

To Find:

• What is the difference between their 4th term ?

Solution: Let the common difference of both AP's be d.

As we know that

★ a^n = a + (n – 1)d ★

[ In first AP ]

• a = first term = –1
• d = common diffrence = d

Its 4th term will be

➟ a⁴ = a + (4 – 1)d

➟ a⁴ = –1 + 3d......(1)

[ In second AP ]

• a = first term = –8
• d = common diffrence = d

Its 4th term will be

➟ a⁴ = a + (4 – 1)d

➟ a⁴ = –8 + 3d......(2)

So, The difference between their 4th term will be

$\implies{\rm }$ (–1 + 3d) – (–8 + 3d)

$\implies{\rm }$ –1 + 3d + 8 – 3d

$\implies{\rm }$ 7

Hence, the difference between their 4th term will be 7.