2.Which of the following numbers
are not perfect cubes?
O
512
O 729
O
216
O 100
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Answer:
100 is correct answer please mark me as brain list rate me
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Answer : option d ) 100
Explanation:
1) Cube root of 512, 3√512 = 8
Since 512 is a perfect cube, we will use here the prime factorisation method, to get the cube root easily.
2) Step 1: Find the prime factors of 729
729 = 3 × 3 × 3 × 3 × 3 × 3
Step 2: Clearly, 729 is a perfect cube. Here we will be using laws of exponents.
729 = 36 [am × an = am+n]
729 = [32]3 [(am)n = amn]
729 = 93
Step 3: Now, we will apply cube root to both the sides of the above expression to take out the factor as a single term, which is in cubes.
3√729 = 3√(93)
So, here the cube root is cancelled by the cube of 9.
Hence, 3√729 = 9
3) Step 1: Find the prime factors of 216
216 = 2 × 2 × 2 × 3 × 3 × 3
Step 2: Clearly, 216 is a perfect cube. Therefore, group the factors of 216 in a pair of three and write in the form of cubes.
216 = (2 × 2 × 2) × (3 × 3 × 3)
216 = 23 × 33
Using the law of exponent, we get;
216 = 63 [ambm = (ab)m]
Step 3: Now, we will apply cube root on both the sides to take out the factor as a single term, which is in cubes.
3√216 = 3√(63)
So, here the cube root is cancelled by the cube of 6.
Hence, 3√216 = 6
4) 100 is not a perfect cube. Now, 1000 is a perfect cube. Thus, the required smallest number is 10.
Hope it helps you :-)
Mark as brainliest answer
Explanation:
1) Cube root of 512, 3√512 = 8
Since 512 is a perfect cube, we will use here the prime factorisation method, to get the cube root easily.
2) Step 1: Find the prime factors of 729
729 = 3 × 3 × 3 × 3 × 3 × 3
Step 2: Clearly, 729 is a perfect cube. Here we will be using laws of exponents.
729 = 36 [am × an = am+n]
729 = [32]3 [(am)n = amn]
729 = 93
Step 3: Now, we will apply cube root to both the sides of the above expression to take out the factor as a single term, which is in cubes.
3√729 = 3√(93)
So, here the cube root is cancelled by the cube of 9.
Hence, 3√729 = 9
3) Step 1: Find the prime factors of 216
216 = 2 × 2 × 2 × 3 × 3 × 3
Step 2: Clearly, 216 is a perfect cube. Therefore, group the factors of 216 in a pair of three and write in the form of cubes.
216 = (2 × 2 × 2) × (3 × 3 × 3)
216 = 23 × 33
Using the law of exponent, we get;
216 = 63 [ambm = (ab)m]
Step 3: Now, we will apply cube root on both the sides to take out the factor as a single term, which is in cubes.
3√216 = 3√(63)
So, here the cube root is cancelled by the cube of 6.
Hence, 3√216 = 6
4) 100 is not a perfect cube. Now, 1000 is a perfect cube. Thus, the required smallest number is 10.
Hope it helps you :-)
Mark as brainliest answer
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