Cubes And Cube Roots 8 Class 8 Exam Prep Revision β Grandmaster Guide
Ayush (Founder)
Exam Strategist
- aΒ³ = a Γ a Γ a
- βa = aΒΉ/Β³
- β(a Γ b) = βa Γ βb
- β(a/b) = βa/βb
- aΒ³/bΒ³ = (a/b)Β³
- βaΒ³ = a
- (aΒ³)ΒΉ/Β³ = a
- β(aΒ³ Γ bΒ³) = a Γ b
- β(aΒ³ Γ· bΒ³) = a Γ· b
πͺ€ The 5 Mistakes That Cost Marks
- Not simplifying cube roots of perfect cubes
- Not using the formula β(a Γ b) = βa Γ βb
- Not using the formula β(a/b) = βa/βb
- Not simplifying expressions with cube roots
- Not checking the units of the answer
βοΈ 3 Solved PYQs
- Question 1: Find the cube root of 125 Step 1: We know that 5Β³ = 125 Step 2: So, β125 = β(5Β³) Step 3: Using the formula β(aΒ³) = a get β125 = 5
- Question 2: Find the cube root of 216 Step 1: We know that 6Β³ = 216 Step 2: So, β216 = β(6Β³) Step 3: Using the formula β(aΒ³) = a get β216 = 6
- Question 3: Find the cube root of 8 Step 1: We know that 2Β³ = 8 Step 2: So, β8 = β(2Β³) Step 3: Using the formula β(aΒ³) = a get β8 = 2
π§ The One Thing Most Students Get Wrong
- Most students get confused between cube and cube root, they think that βa = aΒ³ which is incorrect, βan is the number that when multiplied by itself three times gives a for example β8 = 2 because 2 Γ 2 Γ 2 = 8
ποΈ Ayush's Note
- To find the cube root of a number, try to find the number that when multiplied by itself three times gives the original number
- Use the formula β(a Γ b) = βa Γ βb to simplify expressions with cube roots
- Use the formula β(a/b) = βa/βb to simplify expressions with cube roots
π Last 5 Minutes Box
- Make sure to simplify all expressions with cube roots
- Check the units of the answer
- Use the formula β(aΒ³) = a to simplify expressions with cube roots
- Use the formula β(a Γ b) = βa Γ βb to simplify expressions with cube roots
- Use the formula β(a/b) = βa/βb to simplify expressions with cube roots
π Practice MCQs
1. What is the cube root of 27?
A) 2
B) 3
C) 4
D) 5
Answer: B) 3 because 3 Γ 3 Γ 3 = 27
2. What is the cube root of 64?
A) 2
B) 3
C) 4
D) 5
Answer: C) 4 because 4 Γ 4 Γ 4 = 64
3. What is the cube root of 1?
A) 0
B) 1
C) 2
D) 3
Answer: B) 1 because 1 Γ 1 Γ 1 = 1
4. What is the cube root of 125?
A) 4
B) 5
C) 6
D) 7
Answer: B) 5 because 5 Γ 5 Γ 5 = 125
5. What is the cube root of 8?
A) 1
B) 2
C) 3
D) 4
Answer: B) 2 because 2 Γ 2 Γ 2 = 8
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This post was curated by Jules, Exam Compass Bot, and edited for accuracy by Ayush.
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