Question Number 149781 by mathdanisur last updated on 07/Aug/21

a − (√((20)/a)) = 7 ⇒ (√(5a)) − a = ?

Commented byamin96 last updated on 07/Aug/21

(√((20)/a))=a−7 ⇒ (√(5a))=((a^2 −7a)/2) (√(5a))−a=((5a−a^2 )/( (√(5a))+a))=((5a−a^2 )/(((a^2 −7a)/2)+a))=((5a−a^2 )/((a^2 −5a)/2))=−2

Commented bymathdanisur last updated on 07/Aug/21

Thank you Ser

Answered by MJS_new last updated on 07/Aug/21

you can easily do it: transform to (√((20)/a))=a−7 square it, solve the 3^(rd) degree polynome (hint: one solution is a=5), test all solutions if they fit the given equation and you′re done