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More on equations

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Equations when x is negative

If the value of x is negative, tackle the equation in the same way - aim to get all xs on one side of the equation.

Example 1

Solve the equation 5x - 2 = 12 - 2x

Your aim is to get all the unknown x terms on one of the equation side only, so start by adding 2x to both sides: 7x - 2 = 12
Next add 2 to both sides: 7x = 14
And finally, divide by 7 to give x = 2

As always, you can check your answer in the original equation. So substitute x = 2 back into 5x - 2 = 12 - 2x

(5 × 2) - 2 = 12 - (2 × 2)
10 - 2 = 12 - 4
8 = 8
This makes sense, so the value x = 2 is correct.

Example 2

Solve the equation 4x = 10 - x

Add x to both sides to give 5x = 10.
To find x, divide both sides by 5 to get x = 2

Question

Solve the equation 4x + 1 = 2x + 5

Answer

Start by subtracting 2x from both sides of the equation to give
2x + 1 = 5
Then subtract 1 from each side to give
2x = 4
Divide each side by 2 to give
x = 2

Activity

More on equations activity

Balance your revision with this activity.

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