Question 671904
1. You need to use a calculator since it's impossible to this by hand.

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2.


Are you sure it's not 


-x^3-x^2-5x-5=0 


or


x^3-x^2-5x+5=0 


or is it something else entirely?

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3.


{{{7x^2-144=-x^4}}}


{{{x^4 + 7x^2-144 = 0}}}


{{{(x^2)^2 + 7x^2-144 = 0}}}


{{{z^2 + 7z-144 = 0}}} Let {{{z=x^2}}}


{{{(z+16)(z-9) = 0}}}


{{{z+16 = 0}}} or {{{z-9 = 0}}}


{{{z=-16}}} or {{{z=9}}}


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If {{{z=9}}}, then...


{{{z=9}}}


{{{x^2=9}}}


{{{x=sqrt(9)}}} or {{{x=-sqrt(9)}}}


{{{x=3}}} or {{{x=-3}}}


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If {{{z=-16}}}, then...


{{{z=-16}}}


{{{x^2=-16}}}


but it's impossible for you to multiply a real number by itself to get a negative number. 


So there are NO real numbered solutions in this equation here.


We can find the complex solutions to get


{{{x^2=-16}}}


{{{x=sqrt(-16)}}} or {{{x=-sqrt(-16)}}}


{{{x=4i}}} or {{{x=-4i}}}



So the only real numbered solutions are {{{x=3}}} or {{{x=-3}}}


If you want to throw in the complex solutions, then you would add {{{x=4i}}} or {{{x=-4i}}}, but it will depend on the teacher/book.