问题
解答题
用平方差公式计算:(1)99.8×100.2=______(2)40
|
答案
(1)99.8×100.2,
=(100-0.2)(100+0.2),
=1002-0.22,
=9999.96.
(2)40
×39,1 3
=(40+
)(40-1 3
),1 3
=402-(
)2,1 3
=1599
.8 9
用平方差公式计算:(1)99.8×100.2=______(2)40
|
(1)99.8×100.2,
=(100-0.2)(100+0.2),
=1002-0.22,
=9999.96.
(2)40
×39,1 3
=(40+
)(40-1 3
),1 3
=402-(
)2,1 3
=1599
.8 9