Question

calcule em seu caderno,x,de modo que x^4-8x^2+15

Answer 1

x⁴-8x²+15=0
(x²)²-8x²+15=0

y²-8y+15=0

a=1
b=-8
c=15
_________

∆=b²-4.a.c
∆=(-8)²-4.1.15
∆=64-60
∆= 4
___________
x=-b±√∆
----------
2.a
___________
x= -(-8)±√4
-------------
2.1
__________
x'= +8-2 6
------- = -- = 3
2 2
______________
x" = +8+2 10
-------- = ----- = 5
2 2
________________
PARA Y = 3

X²= 3
x= ±√3
x= ±3
_____________
Para Y = 5

x²= 5
x=±√5
x=±5
____________

S={-3,3,-5,5}