Question If xy=1 , x^2+y^2=2 , find value of x+y Collected in the board: Calculate algebraic expressions Steven Zheng posted 1 year ago
Answer Apply perfect square formula(x+y)^2=x^2+2xy+y^2Substituting xy and x^2+y^2 gives(x+y)^2=2+2\times 1=4 Taking square roots of both sides givesx+y = \pm2 Steven Zheng posted 3 months ago