Question

(x²-4).(x²-1)+5x²=20

Answer 1

( x^{2} -4). ( x^{2} -1)+5 x^{2} =20=>
 2 x^{4} - x^{2} -4 x^{2} -4+5 x^{2} =20=>
2 x^{4} -5 x^{2} +5 x^{2} =20+4=>
 2 x^{4}=24=>
 x^{4}= 24/2=>
 x= \sqrt[4]{12}