高分求几道初二计算题,
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高分求几道初二计算题,
(2x+y)^2-(x+2y)^2
49(a-b)^2-16(a+b)^2
(a-B)x^2+(b-a)Y^2
(2x+y)^2-(x+2y)^2
49(a-b)^2-16(a+b)^2
(a-B)x^2+(b-a)Y^2
![高分求几道初二计算题,](/uploads/image/z/7281922-58-2.jpg?t=%E9%AB%98%E5%88%86%E6%B1%82%E5%87%A0%E9%81%93%E5%88%9D%E4%BA%8C%E8%AE%A1%E7%AE%97%E9%A2%98%2C)
1.(2x+y)^2-(x+2y)^2 =(2x+y+x+2y)*[2x+y-(x+2y)]=(3x+3y)*(x-y) = 3x^2 - 3y^2
2.49(a-b)^2-16(a+b)^2 =[7(a-b)]^2 - [4(a+b)]^2 = [7a-7b + 4a+4b] * [7a-7b -(4a+4b)] =(11a-3b)*(3a-11b)= 33a^2 + 33b^2 -130ab
3.(a-b)x^2+(b-a)Y^2 = (a-b)x^2 - (a-b)Y^2 = (a-b)(x^2 - Y^2) 还可以进一步等于(a-b)(x-y)(x+y)
2.49(a-b)^2-16(a+b)^2 =[7(a-b)]^2 - [4(a+b)]^2 = [7a-7b + 4a+4b] * [7a-7b -(4a+4b)] =(11a-3b)*(3a-11b)= 33a^2 + 33b^2 -130ab
3.(a-b)x^2+(b-a)Y^2 = (a-b)x^2 - (a-b)Y^2 = (a-b)(x^2 - Y^2) 还可以进一步等于(a-b)(x-y)(x+y)