lesson

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Imagine you have a square floor made of 25 identical square tiles, but you need to know how many tiles fit along just one side.
To solve this puzzle, we use two operations that are opposites of each other: squaring and finding the square root.
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How do we undo a power of two when solving an equation with a mystery number?
Solving x2=a
When an equation has a variable multiplied by itself, like x2=49, we undo the square by taking the square root of both sides.
Because both 7ร7=49 and (โ7)ร(โ7)=49, the pure math equation gives two answers: x=7 or x=โ7 (written as x=ยฑ7).
๐Interactive diagram
In geometry and real-life measurements like side lengths, distance cannot be negative, so we only keep the positive root.
What if the square root is already wrapping our mystery number?
Solving xโ=b
To undo a square root sign, we perform its inverse operation by squaring both sides of the equation.
For example, if xโ=6, squaring both sides gives (xโ)2=62, which simplifies directly to x=36.