Bonjour, Pouvez-vous m'aider s'il vous plait

bonjour,

exo 1 :

1) il faut développer et reduire f(x)
(9x²-6x+1)-(x²+4x+4) =
9x²-6x+1-x²-4x-4 =
8x²-10x-3

2) il faut factoriser f(x)
[(3x-1-(x+2)][(3x-1)+(x+2)] =
(3x-1-x-2)(3x-1+x+2) =
(2x-3)(4x+1)

3) image de √7 :
 f(x) = 8x²-10x-3
8(√7)² - 10*√7 -3 =
56-10√7-3 =
-10√7+53

4) antécédents de -3:
f(x) = 8x²-10x-3
8x²-10x-3  =-3
8x²-10x-3+3 = 0
8x²-10x = 0
x(8x-10) = 0
8x-10  =0
8x = 10
x =10/8 = 5/4
x = 0

1) f(x) =(9x²-6x+1)-(x²+4x+4) = 9x²-6x+1-x²-4x-4 = 8x²-10x-3 2) f(x) =[(3x-1-(x+2)][(3x-1)+(x+2)] = (3x-1-x-2)(3x-1+x+2) = (2x-3)(4x+1) 3) f(x) = 8x²-10x-3 8(√7)² - 10*√7 -3 = 56-10√7-3 = -10√7+53 4) f(x) = 8x²-10x-3 8x²-10x-3 =-3 8x²-10x-3+3 = 0 8x²-10x = 0 x(8x-10) = 0 8x-10 =0 8x = 10 x =10/8 = 5/4 x = 0