Question

4/21 и 5/28 к общему знаменателю​

Answer 1

4/21=4×4=16 21×4=84

5/28=5×3=1528×3=84

Ответ:16/84 и 15/84

Answer 2

4/21 и 5/28 общий знаменатель 84

16/84 и 15/84

Answer 3

To find a common denominator for the fractions 4/21 and 5/28, we need to find the least common multiple (LCM) of the denominators 21 and 28.

Step 1: Find the prime factorizations of 21 and 28.

• 21 = 3 * 7
• 28 = 2^2 * 7

Step 2: Take the highest power of each prime that appears in either factorization:

• The highest power of 2 is 2^2 (from 28).
• The highest power of 3 is 3^1 (from 21).
• The highest power of 7 is 7^1 (appears in both 21 and 28).

Step 3: Multiply these highest powers together to get the LCM: LCM = 2^2 * 3^1 * 7^1 = 4 * 3 * 7 = 84

Now, we need to convert the fractions 4/21 and 5/28 to have a common denominator of 84.

For 4/21: We multiply the numerator and denominator by (84/21) to get the equivalent fraction with a denominator of 84. 4/21 * (84/21) = (4 * 84) / (21 * 21) = 336 / 441

For 5/28: We multiply the numerator and denominator by (84/28) to get the equivalent fraction with a denominator of 84. 5/28 * (84/28) = (5 * 84) / (28 * 28) = 420 / 784

Now, both fractions have a common denominator of 84: 4/21 = 336/441 and 5/28 = 420/784.