Question

代数式求值 x÷3y=y÷2x-5y=6x-15y÷x 求4x²-5xy+6y²÷x²-2

Answer 1

x/3y=y/2x-5y

2x^2-5xy-3y^2=0

(x-3y)(2x+y)=0①

x/3y=6x-15y/x

x^2-18xy+45y^2=0

(x-3y)(x-15y)=0②

y/2x-5y=6x-15y/x

xy=3(2x-5y)^2

(x-3y)(12x-25)=0③

若①②③同时成立,

x-3y=0,x=3y

(4x^2-5xy+6y^2)/(x^2-2xy+3y^2)

=[4(3y)^2-5*(3y)*y+6y^2]/[(3y)^2-2*(3y)*y+3y^2]

=9/2