Sagot :
A = (-7x +5)(-7x + 5) + ( -7x +5)(x-7)=0
= (-7x + 5)(-7x + 5 +x - 7)=0
= (-7x + 5)(-6x -2)=0
donc il y a deux solutions:
-7x +5 =0 5 = 7x x = 5/7 = 0,7
et -6x -2 =0 -6x = 2 x = -3
B= (2x+4)²-(2x+4)(-x+12)=0
= (2x+4)(2x+4)-(2x+4)(-x+12)=0
= (2x+4)[2x+4 -(x+12)]
= (2x + 4)(2x + 4 +x -12)
= (2x + 4)(3x - 8)
donc deux solutions :
2x + 4 =0 2x = -4 x = -2
et 3x-8 =0 3x = 8 x = 8/3 = 2,6
C = (-7x+11)²=36
= (-7x + 11)² = 6²
= (-7x + 11)² -6² =0
= (-7x +11 +6)(-7x+11-6) =0
= (-7x +17)(-7x + 5 ) =0
donc deux solutions :
-7x + 17 = 0 17=7x x = 17/7 = 2,4
et -7x+5 = 0 5 = 7x x=5/7 = 0,7
voilà, je crois que c'est ça
