(1)当a=3,b=2时,a2-b2=32-22=9-4=5,(a+b)(a-b)=(3+2)×(3-2)=5; 当a=-5,b=1时,a2-b2=(-5)2-12=25-1=24,(a+b)(a-b)=(-5+1)×(-5-1)=24, 当a=-2,b=-5时,a2-b2=(-2)2-(-5)2=4-25=-21,(a+b)(a-b)=(-2-5)×(-2+5)=-21; 填表为:
(2)由(1)的计算发现:a2-b2=(a+b)(a-b), 故答案为:a2-b2=(a+b)(a-b);
(3)60.062-39.942=(60.06+39.94)×(60.06-39.94)=100×20.12=2012. |