Question

Which term of AP: 3,8,13,18,......78?

Answer 1

Answer:

n=16

Step-by-step explanation:

a=3,d=5

78=a+(n-1)d

78=3+(n-1)5

78=3+5n-5

78-3=5n-5

75=5n-5

5n=75+5

5n=80

n=80/5

n=16

Answer 2

Answer:

$\large\boxed{\star\:\:\:16^{th}\:term\:of\:the\:AP\:is\:78.\:\:\:\star}$

Step-by-step explanation:

☆ Given:-

 AP:- 3,8,13,18,...,78 , where a=3, d=5, aₙ=78.

☆ To Find:-

   nth term of AP(which term of AP is 78).

☆ Formula Applied:-

• aₙ=a+(n-1)d

☆ Solution:-

    aₙ=a+(n-1)d , where aₙ=78, a=3, d=5.

⇒ 78=3+(n-1)(5)

⇒ 78-3=5n-5

⇒ 75+5=5n

⇒ 5n=80

$\implies\: n=\frac{80}{5}$

$\implies\:\boxed{n=16}$