bonsoir pouvez vous m'aider les 3 exercices de la photo svp merci d'avance

bonjour,

29 :
P(x) = 3x²+x-2
b²-4ac = 1²-4(3*-2)  = 1²-4(-6) = 1+24 = 25
Δ = 25 ,>0; 2 solutions
√Δ = 5
(-b-√Δ)/2a = (-1-5)/6 = -6/6 = -1
(-b+√Δ)/2a = (-1+5)/6 = 4/6 =2/3
x1 =-1;x2 = 2/3

P(x) = 0
x = 1
x =-2/3

P(x) = 4x²-28x+49
b²-4ac = -(-28)²-4(4*49) = 784-4*196 =784-784 =0
Δ =0; 1solution
-b/2a = -(-28)/8  =28/8 =7/2

résoudre P(x) = 0
x = 7/2

P(x) = -x²+6x-14
b²-4ac = 6²-4(-1*-14) = 36-4(14) = 36-56
Δ = -20<0; pas de solution dans R