閱讀下列計(jì)算過程:99×99+199=992+2×99+1=(99+1)2=1002=104
(1)計(jì)算:
999×999+1999=______=______=______=______;
9999×9999+19999=______=______=______=______
(2)猜想9999999999×9999999999+19999999999等于多少?寫出計(jì)算過程.
解:(1)根據(jù)99×99+199=992+2×99+1=(99+1)2=1002=104所示規(guī)律,得
999×999+1999=9992+2×999+1=(999+1)2=10002=106;
9999×9999+19999=99992+2×9999+1=(9999+1)2=100002=108.
(2)根據(jù)(1)中規(guī)律,9999999999×9999999999+19999999999=(9999999999+1)2=100000000002=1020.
分析:(1)根據(jù)99×99+199=992+2×99+1=(99+1)2=1002=104所示規(guī)律,通過變形,將999×999+1999和9999×9999+19999化為完全平方的形式,即可輕松計(jì)算;
(2)根據(jù)(1)總結(jié)的規(guī)律,列出完全平方式計(jì)算.
點(diǎn)評(píng):此題是一道規(guī)律探索題,以完全平方公式為依托,展現(xiàn)了探索發(fā)現(xiàn)的過程:由特殊問題找到一般規(guī)律,再利用規(guī)律解題.