Question

x ao quadrado.(x ao quadrado-9)=-20

Answer 1

x^2 . (x^2 -9) = -20
x^4 - 9x^2= -20
x^4 - 9x^2 +20= 0

*x^2 →y*

y^2 -9y + 20 =0
A=1; B=-9; C=20

delta= B^2 -4AC
delta= -9^2 -4. 1. 20
delta= 81- 80
delta=1

y= (-B +/- raiz de delta) ÷ 2A

y= (-[-9] +/- raiz de 1) ÷ 2 . 1

y1= (9 + 1)÷ 2
y1=10÷2

y1=5

y2= (9-1)÷2
y2= 8 ÷2

y2= 4

y→x^2

y1 = x^2
5=x^2

raiz de 5 = x1

y2=x^2
4 =x^2
raiz de 4 = x2

2= x2