bonjour
je ne les fais pas tous
3 x² + 3 x - 6 = 0
delta = 9 - 4 ( 3 * - 6 ) = 9 + 72 = 81 = 9 ²
x 1 = ( - 3 - 9 ) / 6 = - 12 /6 = - 2
x 2 = ( - 3 + 9 ) / 6 = 6 /6 = 1
f (x) = 2 x² - 4 x + 6
f (x) = 2 ( x - 1 )² - 8
f (x) = 2 ( x² - 2 x + 1 ) - 8
f (x) = 2 x² - 4 x + 2 - 8 = 2 x² - 4 x - 6
f (x) = 2 ( x - 3 ) ( x + 1 )
f (x) = ( 2 x - 6 ) ( x+ 1 )
f (x) = 2 x² + 2 x - 6 x - 6
f ( x) = 2 x² - 4 x - 6
f (x) = 0
( 2 x - 6 ) x + 1 ) = 0
Equation produit nul , x = 3 ou - 1
2 x² - 4 x - 6 = - 6
2 x² - 4 x - 6 + 6 = 0
2 x² + 4 x = 0
2 x ( x + 2 ) = 0
x = 0 ou - 2
périmètre = 50 et aire = 114
2a + 2 b = 50
ab = 114
a + b = 25
a = 25 - b
( 25 - b) b = 114
- b² + 25 b - 114 = 0
delta = 625 - 4 ( - 1 * - 114 ) = 625 - 456 = 169 = 13 ²
x 1 = ( - 25 - 13 ) / - 2 = - 38 / - 2 = 19
x 2 = ( - 25 + 13 ) / - 2 = - 12 /2 = 6
rectangle = 6 m sur 19 m
voilà pour 3
