a) The greatest common factor is 3. And the result is 3 × (6 + 7).
b) The greatest common factor is 7. And the result is 7 × (8 + 5).
In this question we must find the greatest common factor, that is, the maximum integer with which can be divided the two number, and take advantage of this result to simplify the sum of the same two numbers, if possible.
First, we proceed to determine the required results for each of the two cases:
18 = 2 × 3 × 3
21 = 3 × 7
Then, the greatest common factor is 3. The complete procedure is:
18 + 21 = 2 × 3 × 3 + 3 × 7 = 3 × (6 + 7)
56 = 2³ × 7
35 = 5 × 7
Then, the greatest common factor is 7. The complete procedure is:
56 + 35 = 2³ × 7 + 5 × 7 = 7 × (8 + 5)
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