用简便方法计算:21×5.79+62×5.79+17×5.79 1.222²×9-1.333²×4
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/21 02:34:05
![用简便方法计算:21×5.79+62×5.79+17×5.79 1.222²×9-1.333²×4](/uploads/image/z/133135-7-5.jpg?t=%E7%94%A8%E7%AE%80%E4%BE%BF%E6%96%B9%E6%B3%95%E8%AE%A1%E7%AE%97%EF%BC%9A21%C3%975.79%2B62%C3%975.79%2B17%C3%975.79+1.222%26%23178%3B%C3%979-1.333%26%23178%3B%C3%974)
用简便方法计算:21×5.79+62×5.79+17×5.79 1.222²×9-1.333²×4
用简便方法计算:21×5.79+62×5.79+17×5.79 1.222²×9-1.333²×4
用简便方法计算:21×5.79+62×5.79+17×5.79 1.222²×9-1.333²×4
21×5.79+62×5.79+17×5.79
=5.79×(21+62+17)
=5.79×100
=579;
1.222²×9-1.333²×4
=(1.222×3+1.333×2)(1.222×3-1.333×2)
=(3.666+2.666)×(3.666-2.666)
=6.332
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