Question

Find all the zeros of the equation.

-4x4 - 44x2 + 3600 = 0

Answer 1

First write the equation as 4x^4 + 44x^2 - 3600 = 0.

Next, factor out a 4, you get x^4 + 11x^2 - 900 = 0.

Now factor the above.

Answer 2

You can also do the trick,
\[z=x^2\Rightarrow z^2+11z-900=0\]And apply,
\[x^2=z=\frac{-b\pm\sqrt{b^2+4ac}}{2a}\]of the usual,
\[ax^2+bx+c=0\]

Answer 3

A. 5, -5, 6i, -6i

B. 5, 6i

C. 5, -5, 6i, 0

D. -5, -6i

Answer 4

The first is the one I would choose.

Answer 5

z = (-11+-61)/2

Answer 6

i got c \

Answer 7

Multiply the four roots of A and tell me what number you obtain.

Answer 8

you can' have just one "i" they come in pairs

Answer 9

if there is a +i there is a corresponding -i

Answer 10

Remember the trick, the product of the roots must be equal to the independent term (that without x) of the equation.

Answer 11

you could also try factoring
this problem has been cooked up so that
\[x^4+11x^2-900\] factors easily

Answer 12

thanks everyone

Answer 13

25 and 36 can be made to fit nicely