Question 200159
{{{x^2+y^2=25}}} Start with the first equation.



{{{x^2+(2x)^2=25}}} Plug in {{{y=2x}}}



{{{x^2+4x^2=25}}} Square 2x to get {{{4x^2}}}



{{{5x^2=25}}} Combine like terms.



{{{x^2=25/5}}} Divide both sides by 5.



{{{x^2=5}}} Reduce



{{{x=sqrt(5)}}} or {{{x=-sqrt(5)}}} Take the square root of both sides (don't forget the "plus/minus"



The solutions above approximate to: {{{x=2.236}}} or {{{x=-2.236}}}



which rounded to the nearest hundredth are: {{{x=2.24}}} or {{{x=-2.24}}}



Now simply plug these values into {{{y=2x}}} to find the corresponding y values to the given x values. I'll let you take over from here.