a: \(203^2-197^2\)
\(=\left(203-197\right)\left(203+197\right)\)
\(=6\cdot400=2400\)
b: \(302\cdot298\)
\(=\left(300+2\right)\left(300-2\right)\)
\(=300^2-2^2=89996\)
c: \(201^2=\left(200+1\right)^2\)
\(=200^2+2\cdot200\cdot1+1^2\)
\(=40000+400+1=40401\)
d: \(198^2=\left(200-2\right)^2\)
\(=200^2-2\cdot200\cdot2+2^2\)
\(=40000-800+4\)
=39204
a)
`203^2 - 197^2`
` = (203 - 197) ( 203 + 197) = 6 . 400 = 2400 `
b)
`302 . 298 = ( 300 + 2) ( 300 - 2) = 300^2 - 2^2 = 90000 - 4 = 89996 `
c)
`201^2 = (200 +1)^2 = 200^2 + 2 . 200 . 1 + 1^2 = 40000 + 400 + 1 = 40401 `
d)
`198^2 = (200 - 2)^2 = 200^2 - 2 . 200 . 2 + 2^2 = 40000 - 800 + 4 = 39204`
