用简便方法计算:1.4²×9-2.3²×36_数学解答

用简便方法计算:1.4²×9-2.3²×36

人气：395 ℃　时间：2020-01-31 05:30:34

解答

1.4²×9-2.3²×36
=1.4²×9-2.3²×4x9
=1.4²×9-4.6²×9
=(1.4+4.6)(1.4-4.6)x9
=6x(-3.2)x9
=-172.8