bonsoir
P(x) = ( x + 4)² - ( 2 x + 3)²
P(x) = x² + 8 x + 16 - ( 4 x² + 12 x + 9)
P(x) = x² + 8 x + 16 - 4 x² - 12 x - 9
P(x) = - 3 x² - 4 x + 7
Factorisation
P(x) = ( x + 4 + 2 x + 3) ( x + 4 - 2 x - 3)
P(x) = ( 3 x + 7) ( - x + 1 )
P(0) = 7 x 1 = 7
P( - 7/3) = ( 3 * - 7/3 + 7) ( 7/3 + 1)
P ( -7/3) = ( - 21/3 + 7) ( 7/3 + 1)
P( -7/3) = ( - 7 + ) ( 7/3 + 1) = 0
P ( √2) = ( 3 √2 + 7) ( - √2 + 1)
P( √2) = - 6 + 3 √2 - 7 √2 + 7
P(√2) = - 4 √2
je te laisse faire la suite avec les tableaux de signes
