2. Find Factor Pairs of 21
Solution:
The factor pairs of 21 are pair of numbers, which are multiplied together resulting in 21
The factor pairs of 21 can be either positive pair or negative pair
Positive factor pairs of 21 :
| 1 | `xx` | 21 | = | 21 | `=>` | (1, 21) |
| 3 | `xx` | 7 | = | 21 | `=>` | (3, 7) |
| 7 | `xx` | 3 | = | 21 | `=>` | (7, 3) |
Since `7` and `3` are already factors of `21`, so we stop here
Hence, Positive factor pairs of 21 are
`(1, 21),(3, 7)`
Negative factor pairs of 21 :
| -1 | `xx` | -21 | = | 21 | `=>` | (-1, -21) |
| -3 | `xx` | -7 | = | 21 | `=>` | (-3, -7) |
| -7 | `xx` | -3 | = | 21 | `=>` | (-7, -3) |
Since `-7` and `-3` are already factors of `21`, so we stop here
Hence, Negative factor pairs of 21 are
`(-1, -21),(-3, -7)`
This material is intended as a summary. Use your textbook for detail explanation.
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