Question 328378
a){{{5x^2=15}}} 
{{{x^2=3}}}
{{{x=0 +- sqrt(3)}}}
b) The x-interepts are the x values when f(x)=0.
{{{f(x)=5x^2-15=0}}}
{{{5x^2=15}}}
Looks familiar?
From a), {{{x=0 +- sqrt(3)}}}
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{{{drawing(300,300,-5,5,-5,5,grid(1),circle(-sqrt(3),0,.2),circle(sqrt(3),0,.2),graph(300,300,-5,5,-5,5,5x^2-15))}}}