Question

Daca x + 1/x =√7, calculati x² + 1/x²

Answer 1

$x+\frac{1}{x}=\sqrt{7}\\\\{x}^{2}+2\times\ x\times\frac{1}{x}+\frac{1}{x^{2}}={\sqrt{7}}^{2}\\\\{x}^{2}+2+\frac{1}{x^{2}}={7}\\\\{x}^{2}+\frac{1}{x^{2}}={7}-2\\\\{x}^{2}+\frac{1}{x^{2}}=5$

Answer 2

Răspuns

5

Explicație pas cu pas: