例1 运用平方差公式计算: (1)(3x+2)(3x-2); (2)(b+2a)(2a-b); (3)(-x+2y)(-x-2y).,分析：在(1)中，可以把3x看成a，2看成b，即 (3x+2)(3x-2)=(3x)2-22,(1)(3x+2)(3x-2) =(3x)2-22 =9x2-4.,(2)(b+2a)(2a-b) =(2a+b)(2a-b) =(2a)2-b2 =4a2-b2,(3)(-x+2y)(-x-2y) =(-x)2-(2y)2 =x2-4y2.,(a + b)(a - b)=a2 - b2,解,例2 计算: (1)10298; (2)(y+2)(y-2)-(y-1)(y+5).,解：(1)10298=(100+2)(100-2) =1002-22=10000-4=9996.,(y+2)(y-2)-(y-1)(y+5) =y2-22-(y2+4y-5) =y2-4-y2-4y+5 =-4y+1.,