Question

6. Arataſi ca numarul 9× .(5+10+15+...+200): 41 este pătrat perfect ​

Answer 1

Răspuns:

Explicație pas cu pas:

Answer 2

$\it 9\cdot(5+10+15+\ ...\ +200):41=9\cdot5\cdot(1+2+3+\ ...\ +40):41=\\ \\ =45\cdot\dfrac{40\cdot41}{2}:41=45\cdot20\cdot41:41=900\cdot1=900=30^2$