7.1) 4x + 3y = 207.2) x^2 - 2xy + y^2 = 257.3) 2x^2 + 5xy - 3y^2 = 07.4) x^3 + y^3 = 647.5) x^2 + 2xy + y^2 = 36
7.1) 4x + 3y = 20
7.2) x^2 - 2xy + y^2 = 25
7.3) 2x^2 + 5xy - 3y^2 = 0
7.4) x^3 + y^3 = 64
7.5) x^2 + 2xy + y^2 = 36