\(\text{a) }301^2\\ =\left(300+1\right)^2\\ =300^2+2\cdot300\cdot1+1^2\\ =90000+600+1\\ =90601\\ \)
\(\text{b) }499^2\\ =\left(500-1\right)^2\\ =500^2-2\cdot500\cdot1+1^2\\ =250000-1000+1\\ =249001\\ \)
\(\text{c) }68\cdot72\\ =\left(70-2\right)\left(70+2\right)\\ =70^2-2^2\\=4900-4\\ =4896\\ \)
a) \(301^2\)
\(=\left(300+1\right)^2\)
\(=300^2+600+1\)
\(=90601\)
b) \(499^2\)
\(=\left(500-1\right)^2\)
\(=500^2-1000+1\)
\(=249001\)
c) \(68\cdot72\)
\(=\left(70-2\right)\left(70+2\right)\)
\(=70^2-2^2\)
\(=4896\)
a) \(301^2\)
\(=\left(300+1\right)^2\)
\(=300^2+2.300.1+1^2\)
\(=90000+600+1\)
\(=90601\)
b) \(499^2\)
\(=\left(500-1\right)^2\)
\(=500^2-2.500.1+1^2\)
\(=250000-1000+1\)
\(=249001\)
c) \(68.72\)
\(=\left(70-2\right)\left(70+2\right)\)
\(=70^2-2^2\)
\(=4900-4\)
\(=4896\)
Chúc bạn học tốt!!!
a) 3012 = ( 300 + 1)2 = 3002 + 600 + 12 = 90000 + 600 + 1 = 90601
b) 4992 = ( 500 - 1 )2 = 5002 - 1000 + 12 = 250000 - 1000 + 1 = 249001
c) 68 . 72 = ( 70 - 2 ) . ( 70 + 2) = 702 - 22 = 4900 - 4 = 4896
a)\(301^2=\left(300+1\right)^2=300^2+2.300.1+1^2=90601\)
b)\(499^2=\left(500-1\right)^2=500^2-2.500.1+1^2=249001\)
c)\(68.72=\left(70-2\right)\left(70+2\right)\)=\(70^2-2^2=4896\)
