因式分解7x²-2xy-3y²

因式分解7x²-2xy-3y²
因式分解7x²-2xy-3y²

因式分解7x²-2xy-3y²
=7(x²-2xy/7+y²/49-22y²/49)
=7[(x-y/7)²-22y²/49]
=7(x-y/7+√22y/7)(x-y/7-√22y/7)

由已知得：x=2y/3，代入欲求式子，得 (7x^2-y^2)/(x^2-2xy 3y^2) =[7*(2y/3)^2-y^2]/[(2y/3)^2-2*2y/3*y 3y^2] =(28y