Question

解方程组 4x + 4y = 20 x * x + y * y =40

Answer 1

4x + 4y = 20 → x + y =5 →x=5-y →代入x * x + y * y =40得(5-y)^2 + y^2=40化简:2y^2 -10y - 15 = 0用根公式得:y =5+√55 或 5-√55所以当y = 5+√55 时,x = 5-√55 当x = 5+√55 时,y = 5-√55...