(x+3y)(x的平方-3xy+9y平方)-(x-3y)(x的平方+3xy+9y平方)这道题目有没有简单的办法所啊最好不用死办法
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![(x+3y)(x的平方-3xy+9y平方)-(x-3y)(x的平方+3xy+9y平方)这道题目有没有简单的办法所啊最好不用死办法](/uploads/image/z/1742900-68-0.jpg?t=%28x%2B3y%29%28x%E7%9A%84%E5%B9%B3%E6%96%B9-3xy%2B9y%E5%B9%B3%E6%96%B9%29-%28x-3y%29%28x%E7%9A%84%E5%B9%B3%E6%96%B9%2B3xy%2B9y%E5%B9%B3%E6%96%B9%29%E8%BF%99%E9%81%93%E9%A2%98%E7%9B%AE%E6%9C%89%E6%B2%A1%E6%9C%89%E7%AE%80%E5%8D%95%E7%9A%84%E5%8A%9E%E6%B3%95%E6%89%80%E5%95%8A%E6%9C%80%E5%A5%BD%E4%B8%8D%E7%94%A8%E6%AD%BB%E5%8A%9E%E6%B3%95)
(x+3y)(x的平方-3xy+9y平方)-(x-3y)(x的平方+3xy+9y平方)这道题目有没有简单的办法所啊最好不用死办法
(x+3y)(x的平方-3xy+9y平方)-(x-3y)(x的平方+3xy+9y平方)这道题目有没有简单的办法所啊最好不用死办法
(x+3y)(x的平方-3xy+9y平方)-(x-3y)(x的平方+3xy+9y平方)这道题目有没有简单的办法所啊最好不用死办法
(a+b)(a²-ab+ab)=a³+b³
(a-b)(a²+ab+ab)=a³-b³
(x+3y)(x的平方-3xy+9y平方)-(x-3y)(x的平方+3xy+9y平方)
=x³+(3y)³-[x³-(3y)³]=54y³
² 都不会打的孩子你伤不起
(x+3y)(x^2-3xy+9y^2)-(x-3y)(x^2+3xy+9y^2) (^是平方的意思)
=(x+3y)(x^2-3xy+9y^2)-(x+3y-6y)(x^2+3xy+9y^2)
=(x+3y)(x^2-3xy+9y^2)-(x+3y)(x^2+3xy+9y^2)+6y(x^2+3xy+9y^2)
=(x+3y)(x^2-3xy+9Y^2-x^2-3x...
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(x+3y)(x^2-3xy+9y^2)-(x-3y)(x^2+3xy+9y^2) (^是平方的意思)
=(x+3y)(x^2-3xy+9y^2)-(x+3y-6y)(x^2+3xy+9y^2)
=(x+3y)(x^2-3xy+9y^2)-(x+3y)(x^2+3xy+9y^2)+6y(x^2+3xy+9y^2)
=(x+3y)(x^2-3xy+9Y^2-x^2-3xy-9y^2)+6y(x^2+3xy+9y^2)
=(x+3y)(-6xy)+6y(x^2+3xy+9y^2)
=-6(x^2)y-18xy^2+6yx^2+18xy^2+54y^3
=54y^3
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