Question

Dado x²-1=6 hallar el valor de x²+x⁻²

Answer 1

x²-1=6
x²=6+1
x²=7

x²+x⁻² =
x²+1/x²
7 + 1/7 =
(49+1)/7 =
50/7       ------ = 7.142857

Answer 2

Ejemplo:
(x + 1)² = (x - 1)² + x²

x² + 2x + 1 = x² - 2x + 1 + x²

2x = x² - 2x

4x = x²

4 = x