bonjour
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
f (x) = 2 x² - 4 x - 6
f (x) = 2 ( x - 3 ) ( x + 1 )
f (x) = 2 ( x² + x - 3 x - 3 )
f ( x) = 2 x² + 2 x - 6 x - 6
f ( x) = 2 x² - 4 x - 6
f ( 1) = 2*1 - 4 *1 - 6 = 2 - 4 - 6 = - 8
f ( 1/3) = 2 ( 1/3)² - 4 *1/3 - 6 = 2 * 1/6 - 4/3 - 6 = 2/6 - 8/6 - 36/6 = 42/6 = 7
f ( √3) = 2 ( √3)² - 4 √3 - 6 = 6 - 4 √3 - 6 = - 4 √3
tracer la fonction sur la calculatrice
je te laisse faire le tableau
2 x² - 4 x - 6 ≤ - 6
2 x² - 4 x - 6 + 6 ≤ 0
2 x² - 4 x ≤ 0
2 x ( x - 2 ) ≤ 0
2 x ≤ 0 ⇔ x ≤ 0
x - 2 ≤ 0 ⇔ x ≤ 2
