Lesson Example Discussion Quiz: Class Homework |
Step-2 |
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 20 multiples of 3 |
|
2 |
Step |
The first 20 multiples of 3 are 3,6,12,….60 |
|
3 |
Clue |
Here |
\$ a = 3,n = 20\$ |
4 |
Hint |
Common difference |
\$d = a_2 - a_1 = 6 - 3 = 3 \$ |
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_20 = 20/2(2(3)+ (20-1)3) \$ |
7 |
Step |
After simplification we get |
\$ S_20 = 10(6 + (19)3)\$ |
8 |
Step |
After simplification we get |
\$ S_20 = 10(6 + 57)\$ |
9 |
Step |
After simplification we get |
\$ S_20 = 10(63)\$ |
10 |
Step |
After simplification we get |
\$ S_20 = 630\$ |
11 |
Step |
The value of \$ S_20\$ is |
630 |
12 |
Answer |
B |
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Tutor: Questions
| Seq | Type | Question | Audio |
|---|---|---|---|
1 |
Problem |
What did you learn from this problem? |
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2 |
Clue |
What did you learn from the clues? |
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3 |
Hint |
What did you learn from the Hints? |
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4 |
Step |
What did you learn from the Steps? |
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5 |
Step |
How can we improve the Steps? |
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