Question

For a given A.P., t7=13, d=-2, then a=?

(Answer with solution)

Options=
A)10
B)15
C)20
D)25

Answer 1

Answer:

Answer is 25

Step-by-step explanation:

Tn = a + (n-1) d

T7 = a +(7-1)(-2)

a = 13-{6×(-2)}

a = 13+12

a = 25

hope my answer helped!!

Answer 2

Answer:

Required value of a is 25.

So, option D is the correct answer.

Step-by-step explanation:

Given,

$t_7 = 13 \\ d = - 2$

We want to find value of a.

Here,$t_7 \: is \: 7th \: term$

and a is first term and d is common difference.

So, common difference is (-2)

We know,$t_n = a + (n - 1)d$

According to question,

$t_7 = 13 \\ a + (7 - 1)( - 2) = 13 \\ a - 12 = 13 \\ a = 13 + 12 \\ a = 25$

Therefore, required first term is 25.

This is a problem of Arithmetic progression.

Extra information about Arithmetic progression:

An arithmetic progression or arithmetic sequence (AP) is a sequence of numbers in which the difference between any subsequent term and the preceding term remains constant throughout the sequence. The constant difference is called the common difference of this arithmetic progression. For example, the sequence 5, 7, 9, 11, 13, 15, . . . is an arithmetic progression with a common difference of 2.

Know more about Arithmetic progression :

1) https://brainly.in/question/4219484

2) https://brainly.in/question/2768711

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