koli123able 3 years ago Factorize x^4-12x^2-64=0

1. mathslover

64 = 8^2 right?

2. koli123able

middle term breaking

3. koli123able

breaking 12x^2

(x^2-16)(x^2+4)

5. mathslover

ok .. : \[\large{x^4+4x^2-16x^2-64=0}\] right?

6. koli123able

absolutely right

7. koli123able

then factorize it again

8. mathslover

ok now .. \[\large{x^2(x^2+4)-16x^2-64=0}\] right?

9. koli123able

(x^2-16)(x^2+4)

(x^2-16)(x^2+4)= (x-4)(x+4)(x^2+4)

11. mathslover

right : \[\large{(a^2-b^2)=(a+b)(a-b)}\]

12. mathslover

\[\large{x^2-4^2=(x+4)(x-4)}\]

13. koli123able

x=+4,-4

14. koli123able

the formula is right but i need to solve this without formula

15. hal_stirrup

hoe do you know that????? x=+4,-4

16. koli123able

x2=16 squaring x=+4,-4

17. koli123able

then after that the hard part

18. koli123able

using x+4=0

19. koli123able

sorry x2+4=0

20. koli123able

x^2=-4 squaring x=+2i,-2i

21. hal_stirrup

you mean x^2+4=0

22. koli123able

yeah

23. koli123able

its done ok fine thanks for help every body