七下数学作业本(2)5.4乘法公式(2)

1.(x+y)^2=x^2+2xy+y^2
(x-y)^2=x^2-2xy+y^2
x^2-4xy+4y^2=(x-2y)^2
2.(3A+B)^2=9A^2+6AB+B^2
(X/2-2Y)^2=X^2/4-2XY+4Y^2
(-X-Y)^2=X^2+2XY+Y^2
199^2=(200-1)^2=40000-400+1=39601
3.(-1+4x)(4x+1)=16x^2-1
(m-3)(-m+3)=-(m-3)^2=-m^2+6m-9
(-3A+B)(-3A-B)=(-3A)^2-B^2=9A^2-B^2
(3A-2B)(-3A-2B)=(-2B)^2-(3A)^2=4B^2-9A^2
4.(A+0.1*2)^2=(A+0.2)^2=A^2+0.4A+0.04
5.A(1-X)^2=A(1-2X+X^2)=A-2AX+AX^2