Question

Daca x²+y²=58 si x-y=4, calculati x+y. Multumesc!

Answer 1

$x^{2} + y^{2} =58=>-( x^{2} - y^{2})=58=>-(x-y)(x+y)=58=> \\ -4(x+y)=58=>x+y= -14,5$
proba: -4*(-14,5)=58