a = b + c + d.
On this we can reason, and produce results which do not belong to any particular number, but are true of all. Thus, if one part be taken away from the number, the other two will remain, or
a - b = c + d.
If each part be doubled, the whole number will be doubled, or
2a = 2b + 2c + 2d.
If we diminish one of the parts, as d, by a number x, we diminish the whole number just as much, or
a - x = b + c + (d - x).
- EXERCISES.
What is a + 2b - c, where a = 12, b = 18, c = 7?—Answer, 41.
| What is | aa - bb |
|---|---|
| ——— | |
| a - b |
where a = 6 and b = 2?—Ans. 8.
What is the difference between (a + b)(c + d) and a + bc + d, for the following values of a, b, c, and d?
| a | b | c | d | Ans. |
|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 10 |
| 2 | 12 | 7 | 1 | 25 |
| 1 | 1 | 1 | 1 | 1 |