Solution of simple linear equations
 |
 |
 |
 |
 |
 |
 |
Further examples of solving simple linear equations
Question 3
aIf 2x + 3y = 6, find x when y = 4.
bIf y = 5x − 10, find x when y = 20.
Solution
| a | 2x + 3 × 4 | = 6 | |
| 2x + 12 | = 6 | (Subtract 12 from both sides of the equation) | |
| 2x | = −6 | (Divide both sides of the equation by 2) | |
| x | = −3. | ||
| Check the answer: LHS | = 2 × −3 + 3 × 4 = 6. | ||
| RHS | = 6. | ||
| b | 20 | = 5x − 10 | |
| 5x − 10 | = 20 | (Add 10 to both sides of the equation) | |
| 5x | = 30 | (Divide both sides of the equation by 5) | |
| x | = 6. | ||
| Check the answer: LHS | = 5x − 10 = 5 × 6 − 10 = 20. | ||
| RHS | = 20. | ||
 |
 |
 |
© Australian Mathematical Sciences Institute, except where indicated otherwise. This material is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported (CC BY-NC 3.0) licence http://creativecommons.org/licenses/by-nc/3.0/
