coolpady72921
如果( - 3 x 2m - 1 y 2n - 1 )( 1 3 x n y m - 1 )= - x 7 y 5...
(-3 x 2m-1 y 2n-1 )( 1 3 x n y m-1 ) =(-3× 1 3 ) (x 2m-1 x n y 2n-1 y m-1 )=-x 2m+n-1...
...其中A种苗的单价为7元/棵,购买B种苗所需费用y(元...
(1)设y与x的函数关系式为:y=kx+b,把(20,160),(40,288)代入y=kx+b得:20k+b=16040k+b=288解得:k=6.4b=32∴y=6.4x...