(1-Y)的平方+(1+Y)的平方 ``=
一个正方形的边长增加3厘米``它的面积就增加39平方厘米``求这个正方形的边长 ``
(P+3Q)的平方-2(P+2Q)(P+3Q)=
(3X+4)的平方-(4X+3)的平方``=
(X-1/2Y)的平方(X=1/2Y)的平方=
2001的平方=``
(X+Y+Z)(X+Y-Z)`=
(X+2Y+)(X+2Y-3)=[`( )+ ][ ( )- ]= ( )
(x+y`)的平方 (x-y)的平方=[( )( ) ]的平方=( )的平方=( )
1.99的平方=( )的平方=( )
(X+3)(X-3)(X的平方-9)=( )
參考答案:解:1)(1-Y)^2+(1+Y)^2=2+2Y^2
2)设正方形的边长为x,则(x+3)^2-x^2=39,即6x+9=39
所以 x=5
3)(P+3Q)^2-2(P+2Q)(P+3Q)=(P+3Q)(-P-Q)
=-P^2-PQ-3PQ-3Q^2=-P^2-4PQ-3Q^2
4)(3X+4)^2-(4X+3)^2=(7X+7)(-X+1)=7-7X^2
5)(X-1/2Y)^2(X+1/2Y)^2=[(X-1/2Y)(X+1/2Y)]^2
=(X^2-1/4Y^2)^2=X^4-1/2X^2Y^2+1/16Y^4
6)2001的平方=(2000+1)^2=4000000+4000+1=4004001
7)(X+Y+Z)(X+Y-Z)=(X+Y)^2-Z^2=X^2+2XY+Y^2-Z^2
8)(X+2Y+3)(X+2Y-3)=[(X+2Y)+3][(X+2Y)-3]
=(X+2Y)^2-9=(X^2+4XY+4Y^2-9)
9)(x+y)^2(x-y)^2=[(x+y)(x-y)]^2
=(x^2-y^2)^2=(x^4-2x^2y^2+y^4)
10)1.99^2=(2-0.01)^2=4-4*0.01+0.0001=3.9601
11)(X+3)(X-3)(x^2-9)=(x^2-9)^2=x^4-18x^2+81
