Help me with surds! maths t

[michiyo84]

kayyy..after surding, I got this answer..

2b^4 - 44b^2 + 144 = 0

the answer is b^2 = 4 or 18
and b = (tambah atau tolak)2 or (tambah atau tolak)3√2 (i dont know how to write 3 surds 2)

how the heck it can get 4 or 18???

[markwongsk]

kayyy..after surding, I got this answer..

2b^4 - 44b^2 + 144 = 0

the answer is b^2 = 4 or 18
and b = (tambah atau tolak)2 or (tambah atau tolak)3√2 (i dont know how to write 3 surds 2)

how the heck it can get 4 or 18???

2b^4 - 44b^2 + 144 = 0

So b^4 - 22b^2 + 72 = 0

So (b^2 - 4)(b^2 - 18) = 0

If the factorization isn't clear, use substitution, eg let b^2 = u and solve the quadratic equation

[michiyo84]

hehe..thank you. i let the b^2 to be X :D