Step-4

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 10 multiples of 5

2

Step

The first 10 multiples of 5 are 5,10,15,…​.50

3

Clue

Here

\$ a = 5,n = 10\$

4

Hint

Common difference

\$d = a_2 - a_1 = 10 - 5 = 5 \$

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_10 = 10/2(2(5)+ (10-1)5) \$

7

Step

After simplification we get

\$ S_10 = 5(10 + (9)5)\$

8

Step

After simplification we get

\$ S_10 = 5(10 + 45)\$

9

Step

After simplification we get

\$ S_10 = 5(55)\$

10

Step

After simplification we get

\$ S_10 = 275\$

11

Step

The value of \$ S_10\$ is

275

12

Answer

C

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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