Exercice 4 svp aidez moi merci BCp merci svp

1) (2n+5)(2n-5) = 4n^2-5^2 = 4n^2-25
2) 205x195=(2*100+5)(2*100-5)=4*100^2-25=40 000-25 = 39 975

bonsoir

( 2 n + 5) ( 2 n - 5) = 4 n² - 25

205 x 195 = ( 200 + 5) ( 200 - 5) = 200² - 5² = 40 000 - 25 = 39 975