数学练习册七年级上第25页的第1,2和最后一题的答案
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数学练习册七年级上第25页的第1,2和最后一题的答案
快点的话再加十分
快点的话再加十分
![数学练习册七年级上第25页的第1,2和最后一题的答案](/uploads/image/z/5991091-43-1.jpg?t=%E6%95%B0%E5%AD%A6%E7%BB%83%E4%B9%A0%E5%86%8C%E4%B8%83%E5%B9%B4%E7%BA%A7%E4%B8%8A%E7%AC%AC25%E9%A1%B5%E7%9A%84%E7%AC%AC1%2C2%E5%92%8C%E6%9C%80%E5%90%8E%E4%B8%80%E9%A2%98%E7%9A%84%E7%AD%94%E6%A1%88)
题目
再问: (x+3y)^2+2(x-y)(x+y)+(x-3y)^2 [ (a-1/2)^2+(a+1/2)^2](2a^2-1/2)
再答: 1.(x+3y)^2+2(x-y)(x+y)+(x-3y)^2 =x^2+6xy+9y^2+2x^2-2y^2+x^2-6xy+9y^2 =4x^2+16y^2 2.[(a-1/2)^2+(a+1/2)^2](2a^2-1/2) =(a^2-a+1/4+a^2+a+1/4)(2a^2-1/2) =(2a^2+1/2)(2a^2-1/2) =4a^2-1/4
再问: (x+3y)^2+2(x-y)(x+y)+(x-3y)^2 [ (a-1/2)^2+(a+1/2)^2](2a^2-1/2)
再答: 1.(x+3y)^2+2(x-y)(x+y)+(x-3y)^2 =x^2+6xy+9y^2+2x^2-2y^2+x^2-6xy+9y^2 =4x^2+16y^2 2.[(a-1/2)^2+(a+1/2)^2](2a^2-1/2) =(a^2-a+1/4+a^2+a+1/4)(2a^2-1/2) =(2a^2+1/2)(2a^2-1/2) =4a^2-1/4