Toán Lớp 8: tính nhanh:
a) 73 ² – 27 ²
b)37 ² – 13 ²
c)2002 ² -2 ²
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Toán Lớp 8: tính nhanh:
a) 73 ² – 27 ²
b)37 ² – 13 ²
c)2002 ² -2 ²
Comments ( 2 )
=(73+27).(73-27)
=100.46
=4600
b)37 ² – 13 ²
=(37-13)(37+13)
=24.50
=1200
c)2002 ² -2 ²
=(2002-2)(2002+2)
=2000.2004
=4008000
Áp dụng hằng đẳng thức:a^2-b^2=(a-b)(a+b)