Question

equação biquadratica
$2x {}^{4} -x {}^{2} - 15 = 0$

Answer 1

x2 = Y

2[ ( x ) 2 ] 2 - x2 - 15 = 0
2y2 - y - 15 = 0
∆ = 1 + 120
∆ = 121

Y = ( 1 + 11 ) / 4
Y = 12 / 4
Y = 3

Y = ( 1 - 11 ) / 4
Y = - 10 / 4
Y = - 5 / 2 ( n serve )

x2 = 3
x = √3
x = +√3 e - √3