Question

先化简再求值x²-6xy+9y²分之x²-3xy 其中x=-1 y=3分之2

Answer 1

原式为：x²-3xy／x²-6xy+9y²
=x(x－3y)／(x－3y)²
=x／x－3y
再将x=-1 y=3分之2代入，有
原式=x／x－3y
=﹣1／（﹣1）－3×2／3
=1／3

Answer 2

(X^2-6XY+9Y^2)/(X^2-3XY)
=(X-3Y)^2/x(x-3y)
=(x-3y)/x
=1-3y/x
1-3y/x=1-(3*2/3)/(-1)=1+2=3