Culegere Matematica Clasa A 9 A May 2026

“The equations force the son to be 9 and the father 36, with sum 45. Since 45 is composite (3 × 15, 5 × 9), the condition ‘sum is prime’ cannot be met. Therefore, no such ages exist in whole numbers.”

He had learned something the culegere never said out loud: sometimes the right answer is that there is no answer—and explaining why is the real solution. culegere matematica clasa a 9 a

One rainy Thursday, he flipped to a random page. Problem 789: A father is three times as old as his son. In 12 years, he will be twice as old. Find their ages. “The equations force the son to be 9

That night, he didn’t stop at three problems. He solved five. Then ten. By December, the blue culegere was battered but beloved. And when his teacher asked the class, “Who enjoys the challenge problems at the end of each chapter?” Andrei raised his hand. One rainy Thursday, he flipped to a random page