Réponses

2013-03-24T15:52:00+01:00
1ère : 3x + 3 = 138
3x=135
x= 135/3 = 45

2ème : 3x + 300 = 1440
3x = 1140
x = 1140/3 = 380

3ème x+4x =90
5x=90
X = 90/5 = 18

5eme (x-12)(x+20) = x2
x2 + 20x - 12x - 240 = x2
X2-x2 + 8x = 240
8x =240
X= 240/8 = 30

4ème : x+280= 1440
x= 1440-280 = 1160