Question

Determina toate numerele de forma xy,stiind că x9y > 795​

Answer 1

Explicație pas cu pas:

x9y > 795 => x ≥ 7

x = 7 => 79y > 795 => 796, 797, 798, 799

=> xy ∈ {76,77,78,79}

x = 8 => 89y > 795 => y ∈ {0,1,2,3,4,5,6,7,8,9}

=> xy ∈ {80,81,82,83,84,85,86,87,88,89}

x = 9 => 99y > 795 => y ∈ {0,1,2,3,4,5,6,7,8,9}

=> xy ∈ {90,91,92,93,94,95,96,97,98,99}

putem scrie: 76 ≤ xy ≤ 99