Hello,
1)
0.25 ((1 + 5)² - (1 - 5)²) = 0.25(6)²-(-4)² = 0.25 * 36 - 16 = 0.25 * 20 = 5
2)
0.25((-2 - 3)² - (-2 + 3)²) = 0.25((4+ 12 + 9) - (4 - 12 + 9)) = 0.25 * 24 = 6
3)
0.25((a + b)² - (a - b)²)) = 0.25(a² + 2ab + b² - (a² - 2ab + b²)) = 0.25(a² + 2ab + b² - a² +2ab -b²]) = 0.25(4ab) = 1/4 * 4ab = ab
Il a raison.
bonjour,
A = 1/4 [(a + b)² - ( a - b) ²]
A = 1/4 ( a + b + a - b) ( a + b - a + b)]
A = 1/4 [( a²) ( b²) ]
pour a = 1 et b = 5
A = 1/4 ( 1 x 25) = 1/4 x 25 = 25/4 = 5
pour a = - 2 et b = - 3
A = 1/4 [ ( - 2 - 3 )² - ( - 2 + 3)²]
A = 1/4 [ ( - 5)² - ( 1)²}
A = 1/4 ( 25 - 1 ) = 1/4 x 24 = 24/4 = 6
donc il a raison