Réponses

2014-02-03T17:11:26+01:00
Bonjour
1)
15
15 -5 = 10
10² = 100
100 -9 = 91
91

2) P(10)
10
10-5 = 5
5² = 25
25 -9 = 16
16

P(20)
20
20-5 = 15
15² = 225
225 -9 = 216
216

P(-10)
-10
-10-5 = -15
-15² = 225
225-9 = 216
216

3)
x
x-5
(x-5)² = x² -10x +25
x² -10x +25 -9
x² - 10x  +16

4) (x-5)² -9 = (x-5-3)(x-5+3) = (x -8)(x -2)

5) x² -10x +16 = 0
x(x - 10 +16) = 0
x(x +6) = 0
soit x = 0
soit x = -6

tu fais pareil pour 72