Step-3

Title: The sum of arithmetic progression

Grade: 9-a Lesson: S4-L2

Explanation: Hello Students, time to practice and review the steps for the problem.

Lesson Steps

Step Type Explanation Answer

1

Problem

Find the sum of the first 30 multiples of 2

2

Step

The first 30 multiples of 2 are 2,4,6,…​.60

3

Clue

Here

\$ a = 2,n = 30\$

4

Hint

Common difference

\$d = a_2 - a_1 = 4 - 2 = 2 \$

5

Formula:

Sum of n terms of an AP

\$ S_n = n/2(2a+(n-1)d)\$

6

Hint

Substitute \$a,d,n\$ values in formula

\$S_30 = 30/2(2(2)+ (30-1)2) \$

7

Step

After simplification we get

\$ S_30 = 15(4 + (29)2)\$

8

Step

After simplification we get

\$ S_30 = 15(4 + 58)\$

9

Step

After simplification we get

\$ S_30 = 15(62)\$

10

Step

After simplification we get

\$ S_30 = 930\$

11

Step

The value of \$ S_30\$ is

930

12

Answer

A

Tutor: Questions

Seq Type Question Audio

1

Problem

What did you learn from this problem?

2

Clue

What did you learn from the clues?

3

Hint

What did you learn from the Hints?

4

Step

What did you learn from the Steps?

5

Step

How can we improve the Steps?


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