Sagot :
Réponse :
déterminer les expressions affines suivantes:
1) f(- 3) = - 19 et f(4) = 9
f(x) = a x + b
{ - 3 a + b = - 19
{ 4 a + b = 9
.......................................
- 3 a - 4 a + b - b = - 19 - 9 ⇔ - 7 a = - 28 ⇔ a = 28/7 ⇔ a = 4
4*4 + b = 9 ⇔ b = 9 - 16 = - 7
f (x) = 4 x - 7
2) g(3) = - 4 et g(9) = 8
{ 3 a + b = - 4
{ 9 a + b = 8
..............................
3 a - 9 a = - 4 - 8 ⇔ - 6 a = - 12 ⇔ a = 12/6 ⇔ a = 2
9*2 + b = 8 s étape par étape
⇔ b = 8 - 18 ⇔ b = - 10
g (x) = 2 x - 10
3) h(- 1) = 32 et h(2) = - 4
{ - a + b = 32
{ 2 a + b = - 4
.....................................
- a - 2 a = 32 + 4 ⇔ - 3 a = 36 ⇔ a = - 36/3 ⇔ a = - 12
- (-12) + b = 32 ⇔ b = 32 - 12 ⇔ b = 20
h (x) = - 12 x + 20
Explication
