Nice Algebra Math Simplification | Find the Value of X

Nice Algebra Math Simplification | Find the Value of X

[@shpark850]

1. Substitute x^2 = A 2. Then, A^2 + A - 20 = 0 3. Factorizing gives: (A + 5)(A - 4) = 0 4. Therefore, A = -5 or 4. 5. discard -5 as it is a complex root. What remains is: A = x^2 = 4. 6. Therefore, x = +2, -2.

[@nucki222]

I have the same solution

[@PrithwirajSen-nj6qq]

No please do not discard complex roots. As it is a biquadratic / quartic equation where the highest power of x is 4 , it do have 4 roots. Thanks.

[@mohinkhan2503]

4

[@PrithwirajSen-nj6qq]

The given equation is a bi quadratic / quartic equation in quadratic form. x^4 + x^2 - 20=0 > (x^2 + 5)(x^2-4) =0 When x^2 +5 =0 , then x^2 = - 5 x=+/-√5 i ( as - 1=i^2) When x ^2 + 4 =0 , then x=+/-2 Biquadratic / quartic equation do have 4 solutions .

[@angelaramosmelo6247]

2

[@amitavadasgupta6985]

x has 2 real roots =+/-1 and 2 complex.

[@drisslahlou2726]

ac=-20 et b=1 doncsolution 5et -4 car 5-4 =1et 5x-4 =-20