Extending square garden

Mrs. Petrová's garden had a square shape with a side length of 15 m. After its enlargement by 64 m² (square), it became a square again. How many meters has the length of each side of the garden been extended?

Correct answer:

x =  2 m

Step-by-step explanation:

$$\begin{gathered} a=15\text{m} \\ {S}_2=64{\text{m}}^2 \\ {a}^2+S_2=b^2 \\ b=\sqrt{a^2+S_2}=\sqrt{15^2+64}=17\text{m} \\ x=b-a=17-15=2\text{m} \end{gathered}$$

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