Question

Va rog foarte frumos ex 18 (doar a,b,c si d) 19 si 20!!!! Dau coroana!!!

Answer 1

Răspuns:

Explicație pas cu pas:

a)

M(0, 3) apartine de grafic =>

f(0) = 3

a * 0 + b = 3

b = 3

P(1, 7) apartine de grafic =>

f(1) = 7

a * 1 + b = 7

a + b = 7

Stiind ca b = 3 =>

a + 3 = 7

a = 7 - 3

a = 4

b)

M(0, -1) apartine de grafic =>

f(0) = -1

a * 0 + b = -1

b = -1

P(2, 3) apartine de grafic =>

f(2) = 3

a * 2 + b = 3

2 * a + b = 3

Stiind ca b = -1 =>

2 * a + (-1) = 3

2 *a - 1= 3

2 * a = 3 + 1

2 * a = 4

a = 4 : 2

a = 2

c)

M(1, 5) apartine de grafic =>

f(1) = 5

a * 1 + b = 5

a + b = 5

P(3, 9) apartine de grafic =>

f(3) = 9

a * 3 + b = 9

3 * a + b = 9

$\left \{ {{a + b = 5} \atop {3 * a + b = 9}} \right.$

b = 5 - a

3 * a + (5 - a) = 9

3 * a + 5 - a = 9

2 * a + 5 = 9

2 * a = 9 - 5

2 * a = 4

a = 4 : 2

a = 2

b = 5 - a

b = 5 - 2

b = 3

d)

M(-2, 5) apartine de grafic =>

f(-2) = 5

a * (-2) + b = 5

P(5, 12) apartine de grafic =>

f(5) = 12

$\left \{ {{a * (-2) + b = 5} \atop {a * 5 + b = 12}} \right.$

b = 5 - (-2) * a

b = 5 + 2 * a

5 * a + (5 + 2 * a) = 12

5 * a + 5 + 2 * a = 12

7 * a + 5 = 12

7 * a = 12 - 5

7 * a = 7

a = 7 : 7

a = 1

b = 5 + 2 * a

b = 5 + 2 * 1

b = 5 + 2

b = 7