Question 107509
Not fair getting around the 6 question per day limit by asking about multiple problems.  I'll do 2 of them:


{{{x^2-4=0}}}


Remember that {{{(a+b)(a-b)=a^2-b^2}}}, so


{{{x^2-4=(x+2)(x-2)=0}}}

{{{x+2=0}}} or
{{{x-2=0}}}


{{{x=-2}}} or {{{x=2}}}

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{{{3x+x^2=0}}}

Factor out an x:

{{{x(3+x)=0}}}

{{{x=0}}} or
{{{x+3=0}}}

So {{{x = 0}}} or {{{x = -3}}}


Hint for #3:  It won't factor, use the Quadratic Formula

Hint for #4:  Divide through by 4 first to get rid of the >1 coefficient on the {{{x^2}}} term.

I'll leave checking the answers to you.  Remember, each problem has two answers, so you have to check both.