Question

the sum of a 15 terms of AP 4,7,10,is ....​

Answer 1

Answer:

Step-by-step explanation:

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Answer 2

Given: An AP consists of the following terms:

4,7,10 . . .

To find: Sum of 15 terms of this AP

Solution: Let the first term be denoted by a and common difference be denoted by d.

The first term of this AP is 4

The common difference of an AP is equal to the difference between any two terms of an AP.

d = 7-4 = 3

a= 4

Sum of n terms of an AP is given by the formula:

$\frac{n}{2} (2a + (n - 1)d)$

$= \frac{15}{2} (2 \times 4 + (15 - 1) \times 3)$

$= \frac{15}{2} (8 + 14 \times 3)$

$= \frac{15}{2} (8 + 42)$

$= \frac{15}{2} \times 50$

$= 15 \times 25$

= 375

Therefore, the sum of 15 terms of this AP is equal to 375.