利用平方差公式计算:(1)37×43(2)6.9×7.1

利用平方差公式计算:(1)37×43(2)6.9×7.1
2025-06-25 22:26:12
推荐回答(1个)
回答1:

(1)37×43,
=(40-3)(40+3),
=40 2 -3 2
=1600-9,
=1591;

(2)6.9×7.1,
=(7-0.1)(7+0.1),
=7 2 -0.1 2
=49-0.01,
=48.99.