bonjour,
1) factoriser A
A = 2(x+3)²+2(x+3)
(x+3)[2(x+3)+2] =
(x+3)(2x+6+2) =
(x+3)(2x+8) =
2(x+3)(x+4)
b) developper :
2(x²+6x+9)+2x+6 =
2x²+12x+18+2x+6 =
2x²+14x+24
c) tu remplaces x par 0 et 1 dans 2x²+14x+24
je te fais √7
2(√7)² + 14*√7 + 24 =
2*7 + 14√7 + 24 =
14√7+38
d) A(x) =0
2(x+3)(x+4) = 0
x=3 = 0
x =-3
x+4 =0
x = -4
e) 2x²+14x+24 = 24
2x²+14x+24-24 =0
2x²+14x =0
2x(x+7) = 0
x=7 =0
x =-7
2x =0
x = 0