Substitute values into simple linear equations
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Question 3
a
If 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. |
| b | 20 | = 5x − 10 | ||
| 30 | = 5x | (Add 10 to both sides of the equation) | ||
| x | = 6. | (Divide both sides of the equation by 5) | ||
| Check the answer: 5x − 10 = 5 × 6 − 10 = 20. | ||||
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