Question 263737
Please help me solve this equation: {{{ 3*x^-4-21*x^-2+3=0 }}}

3*x^-4-21*x^-2+3=0  multiply this equation by x^4

3_21x^2+3x^4=0

3x^4-21x^2+3=0   common factor 3

x^4-7x^2+1=0

x^2(x^2-7)+ 1 =0   Divide by x^2

x^2-7 +1/x^2=0

x^2+1/x^2-7=0
x^2+2+1/x^2-9=0

(x+1/x)^2-9=0

(x+(1/x)+3)(x+(1/x)-3)=0