(1):(x+2y)²-(x+y)(3x-y) (2):(2x+3y)²-(2x-3y)²

问题描述:

(1):(x+2y)²-(x+y)(3x-y) (2):(2x+3y)²-(2x-3y)²
(3):2a(5a-2分之1b²)-3a(5a-b²) (4):(9x³y²-6xy+3xy²)÷(-3xy) (5):化简求值:(2x+y)²-(2x-y)(x+y)-2(x-2y)(x+2y),其中x+2分之1,y=2 (6):先化简(2x-1)²-(3x+1)(3x-1)+5x(x-1),再选取一个你喜欢的数代替x,并求原代数式的值 求求求!

(1):(x+2y)²-(x+y)(3x-y) =x²+4xy+4y²-3x²+xy-3xy+y²=-2x²+2xy+5y²(2):(2x+3y)²-(2x-3y)²=(2x+3y+2x-3y)(2x+3y-2x+3y)=4x*6y=24xy(3):2a(5a-2分...