Question

determinati nr nat x care verifica relatiile ​

Answer 1

x∈N

$a) {3}^{x + 3} = 243 \\ {3}^{x} \times 27 = 243 \\ {3}^{x} = 9 \\ x = 2 \\ \\ b) \: {x}^{3} < 150 \\ x < \sqrt[3]{150} \\ \sqrt[3]{125} < \sqrt[3]{150} < \sqrt[3]{216} \\ 5 < \sqrt[3]{150} < 6 \\ = > x = 0,1,2,3,4,5 \\ \\ c) \: {2}^{x + 3} - 5 \times {2}^{x} = 48 \\ {2}^{x} \times 8 - 5 \times {2}^{x} = 48 \\ {2}^{x} (8 - 5) = 48 \\ {2}^{x} = 16 \\ x = 4$