求一道数学题..一点不难1.899×901+1 要过程(整式乘法)谢..我24小时一直都在...还有一个 ...2.(-x+2y+3z)(-x+2y-3z)
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![求一道数学题..一点不难1.899×901+1 要过程(整式乘法)谢..我24小时一直都在...还有一个 ...2.(-x+2y+3z)(-x+2y-3z)](/uploads/image/z/1721079-63-9.jpg?t=%E6%B1%82%E4%B8%80%E9%81%93%E6%95%B0%E5%AD%A6%E9%A2%98..%E4%B8%80%E7%82%B9%E4%B8%8D%E9%9A%BE1.899%C3%97901%2B1+%E8%A6%81%E8%BF%87%E7%A8%8B%EF%BC%88%E6%95%B4%E5%BC%8F%E4%B9%98%E6%B3%95%EF%BC%89%E8%B0%A2..%E6%88%9124%E5%B0%8F%E6%97%B6%E4%B8%80%E7%9B%B4%E9%83%BD%E5%9C%A8...%E8%BF%98%E6%9C%89%E4%B8%80%E4%B8%AA+...2.%EF%BC%88-x%2B2y%2B3z%29%28-x%2B2y-3z%29)
求一道数学题..一点不难1.899×901+1 要过程(整式乘法)谢..我24小时一直都在...还有一个 ...2.(-x+2y+3z)(-x+2y-3z)
求一道数学题..一点不难
1.899×901+1 要过程(整式乘法)
谢..我24小时一直都在...
还有一个 ...2.
(-x+2y+3z)(-x+2y-3z)
求一道数学题..一点不难1.899×901+1 要过程(整式乘法)谢..我24小时一直都在...还有一个 ...2.(-x+2y+3z)(-x+2y-3z)
1.899×901+1
=(900-1)(900+1)+1
=900²-1²+1
=810000
原理:(a+b)(a-b)=a²-b²
2.(-x+2y+3z)(-x+2y-3z)
=[(-x+2y)+3z][(-x+2y)-3z]
=(-x+2y)²-(3z)²
=x²-4xy+4y²-9z²
原理:①同上但原式中a=-x+2y为一个式子
②(a±b)²=a²±2ab+b²
=(900-1)*(900+1)+1
=900^2-1^2+1
=900^2
=810000
1.
899×901+1 =899*900+899+1
=899*900+900=900*(899+1)=900*900=810000
2.
(-x+2y+3z)(-x+2y-3z) =
(2y-x)^2-9z^2
899*901+1=(900-1)*(900+1)+1=900*900=810000
(-x+2y+3z)(-x+2y-3z)
=(-x+2y)^2-(3z)^2
=4y^2+x^2-4xy-9z^2
=(900-1)(900+1)+1=900*900-1*1+1=810000
是899*901+1吧
899×901+1
=(900-1)(900+1)+1
=900^2-1+1
=900^2
=810000
(-x+2y+3z)(-x+2y-3z)
=【(-x+2y)+3z】【(-x+2y)-3z】
=(-x+2y)^2-9Z^2
=x^2-4xy+4y^2--9Z^2
=(900-1)*(900+1)+1
=900²-1+1
=810000
运用的是(a-b)*(a+b)=a²-b²