Solving linear equations
Finding the value of the unknown letter by doing the same thing to both sides until the letter is alone.
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Analogy
Like a balanced set of scales: whatever you add or remove on one side, you must do on the other.
Example
Take 5 from both sides: 3x = 15Divide both sides by 3: x = 5Check: 3 x 5 + 5 = 20
In practice
If a plumber charges 5 pounds plus 3 pounds per hour and the bill is 20 pounds, you solve 3x + 5 = 20 to find the hours.
Practice
Flashcards
- Solve 3x + 5 = 20.x = 5. Take 5 from both sides, then divide by 3.
Questions people ask
What is the first step in solving an equation?
Undo the addition or subtraction first, then undo the multiplication or division. In 3x + 5 = 20, take away 5 from both sides before dividing by 3. You are working backwards through BIDMAS to isolate the letter. Always check by putting your answer back in at the end, as that shows whether the steps were correct.
How do you check your answer to an equation?
Put your answer back into the original equation. If both sides are equal, it is correct. For 3x + 5 = 20 with x = 5, the left side is 15 + 5 = 20, which matches the right side.