33 svp merci de m'aider je comprends pas c'est un dm pour jeudi

bonsoir

1/
(3x+1)²-49
9x²+6x+1+49
9x²+6x+50
2/
(3x+1)² -49
(3x+1)² -7²
(3x+1-7)(3x+1+7)
(3x-6)(3x+8)
2(x-3)(3x+8)
3/
f 0
9x²+6x+50
9(0)²+6(0)+50
0+0+50
50

f1/3
9x²+6x+50
9(1/3)² +6(1/3) +50
9(1/9) +6/3 +50
9/9 +2+50
1+2+50
53

f 2
(3x+1)² -49
(3*2 +1)² -49
(6+1)² -49
7²-49
49-49
0


f (v5)
9x²+6x+50
9(V5)² +6V5 +50
9(5) +6V5+50
45+6V5+50
6V5 +95

b) fx =0

(3x-6)(3x+8) =0

3x-6 = 0                  3x+8 =0
3x = 6                         3x = -8
x = 6/3 = 2                   x = -8/3

c)
fx = x²

9x²+6x+50 = 9x²
9x²+6x+50 -9x² =0
6x+50 =0
6x = -50
x = -50/6
x = -25/3