3. A student arranged pieces of candy in a square arrangement, but had \( 15 \) pieces left over. After adding \( 20 \) pieces they were able to make a larger square arrangement. How many pieces did the student start with?
Pregunta
Answer
\(a^{2} + 15+ 20= b^{2}\)
\((b+ a)(b- a)= 5\times 7\)
b+a=7
b-a=5
b=6,a=1
so the student starts with 1+15=16 pieces.
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