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# Help. ​

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Help.

NotSoSmart  Dec 1, 2017

#1
+5552
+1

-3x4 + 27x2 + 1200  =  0

First, let's divide each term by  -3  .

x4 - 9x2 - 400  =  0

Now, notice that we can write  x4  as  (x2)2 .

(x2)2 - 9x2 - 400  =  0

And this factors as...

(x2 - 25)(x2 + 16)  =  0            Set each factor equal to zero.

x2 - 25  =  0          or          x2 + 16  =  0

x2  =  25               or           x2  =  -16

Now we can solve each equation for  x  by taking the ± square root of both sides.

x  =  ± 5          or          x  =  ± 4i

So all the zeros are   5 ,  -5 ,  4i , and  -4i

hectictar  Dec 1, 2017
Sort:

#1
+5552
+1

-3x4 + 27x2 + 1200  =  0

First, let's divide each term by  -3  .

x4 - 9x2 - 400  =  0

Now, notice that we can write  x4  as  (x2)2 .

(x2)2 - 9x2 - 400  =  0

And this factors as...

(x2 - 25)(x2 + 16)  =  0            Set each factor equal to zero.

x2 - 25  =  0          or          x2 + 16  =  0

x2  =  25               or           x2  =  -16

Now we can solve each equation for  x  by taking the ± square root of both sides.

x  =  ± 5          or          x  =  ± 4i

So all the zeros are   5 ,  -5 ,  4i , and  -4i

hectictar  Dec 1, 2017

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