用简便方法计算:21.5^2-3*21.5+1.5^2-100
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用简便方法计算:21.5^2-3*21.5+1.5^2-100
![用简便方法计算:21.5^2-3*21.5+1.5^2-100](/uploads/image/z/8555193-9-3.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%9A21.5%5E2-3%2A21.5%2B1.5%5E2-100)
21.5^2-3*21.5+1.5^2-100
=21.5*21.5-3*21.5+1.5^2-100
=(21.5-3)*21.5+1.5^2-100
=18.5*21.5+1.5^2-100
=18.5*(20+1.5)+1.5^2-100
=18.5*20+18.5*1.5+1.5*1.5-100
=18.5*20+(18.5+1.5)*1.5-100
=18.5*20+1.5*20-100
=(18.5+1.5)*20-100
=400-100
=300
=21.5*21.5-3*21.5+1.5^2-100
=(21.5-3)*21.5+1.5^2-100
=18.5*21.5+1.5^2-100
=18.5*(20+1.5)+1.5^2-100
=18.5*20+18.5*1.5+1.5*1.5-100
=18.5*20+(18.5+1.5)*1.5-100
=18.5*20+1.5*20-100
=(18.5+1.5)*20-100
=400-100
=300
用简便方法计算:21.5^2-3*21.5+1.5^2-100
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