Question 742094
{{{sqrt(20-x)+8=sqrt(9-x)+11}}}



{{{sqrt(20-x)-sqrt(9-x)=11-8}}}


{{{sqrt(20-x)-sqrt(9-x)=3}}}



square both sides



{{{(sqrt(20-x)-sqrt(9-x))^2=9}}}



{{{20-x+9-x -2sqrt((20-x)(9-x))=9}}}


{{{29-2x -2sqrt((20-x)(9-x))=9}}}


{{{ -2sqrt((20-x)(9-x))=9-29+2x}}}


square both sides


{{{4(20-x)(9-x)=(-20+2x)^2}}}


{{{4(180-29x+x^2)=400-80x+4x^2}}}


/4

{{{180-29x+x^2=100-20x+x^2}}}


9x=80