Equations

Hong Kong

Stage 1 - Stage 3

Lesson

We want to keep equations balanced so that the two sides of the equals sign remain equivalent. If we don't we could change what the equation means. Think of a balanced set of scales. The scale remains level when the weights on both side of the scales are even. The same thing happens with equations.

This shows a *balanced* equation.

If we add a weight to one side and not to the other, then the scales will no longer be balanced.

Beginning with the equation $x=8$`x`=8, write the new equation produced by adding 2 to both sides.

**Think:**

**Do:** $x+2=10$`x`+2=10

Beginning with the equation $x=-99$`x`=−99, write the new equation produced by dividing both sides by 11.

**Think: **

**Do:** $\frac{x}{11}=-9$`x`11=−9

Beginning with the equation $33x=99$33`x`=99, write the new equation produced by dividing both sides by 11.

**Think:** Just like before, we need to divide both the left and right side of the equation by 11.

**Do:** $3x=9$3`x`=9

Beginning with the equation $x=14$`x`=14, write the equation produced by subtracting $7$7 from both sides.

Beginning with the equation $x=99$`x`=99, write the equation produced by dividing both sides by $11$11.

Remember

Keep equations balanced by always performing the exact same operation to both sides of the equation.