Question 641699

one number  {{{x}}} is {{{7}}} more than another number {{{y}}};

{{{x=y+7}}}.........1

 and its square {{{x^2}}}is {{{77}}} more than the square of the smaller  {{{y^2}}}

{{{x^2=y^2+77}}}...............2
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{{{x=y+7}}}.........1
{{{x^2=y^2+77}}}...............2.....solve the system
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{{{x=y+7}}}.........1...plug in 2 and solve for {{{y}}}

{{{(y+7)^2=y^2+77}}}...............2


{{{y^2+14y+49=y^2+77}}}


{{{cross(y^2)+14y=cross(y^2)+77-49}}}

{{{14y=28}}}

{{{y=28/14}}}

{{{highlight(y=2)}}}...now find {{{x}}}

{{{x=2+7}}}.........1

{{{highlight(x=9)}}}