当4x=5y时,y不等于0,则x²-y²/y²的值为?
问题描述：
当4x=5y时,y不等于0,则x²-y²/y²的值为?
答
9
答
X=5/4 y (25/16 y^2-y^2)/y^2=9/16
答
4x=5y x=5/4y x²-y²/y² =x²-y²+2xy-2xy/y²=(x-y)²+2xy/y²,带入x=5/4y得：（5/4y-y)²+2 X 5/4y X Y / y...