Question

Solve
the equation
x^4-9x^2+20=0​

Answer 1

Step-by-step explanation:

Given x^4-9x^2+20=0 ------(1)

Let t = x^2

squaring on both side

t^2 = x^4

(1) becomes

t^2 - 9t + 20 = 0

(t-5)(t-4) = 0

t-5 = 0 t-4 = 0

t = 5 t = 4

Therefore

${x}^{2} = 5 \: \: \: \: {x}^{2} = 4$

$x = \sqrt{5} \: \: \: \: x = \sqrt{4}$

$x \: = { + \sqrt{5} \: \: \: - \sqrt{5} }$

$x \: = + 2 \: \: - 2$