Question

zadanie 18,20 str 67 z podr klasa 8 (dam naj)​

Answer 1

18.

a) 7x - 6 = - 6x + 7

13 x = 13

x = 1

b) 1/3x + 2 = x

- 2/3x = - 2

2/3x = 2 / *3/2

x = 3

c) -7(2x + 1) = 4

-14x - 7 = 4

-14x = 11 / : (-14)

x = -11/14

d) 8 = 6(x - 1) - 4x

8 = 6x - 6 - 4x

2x = 14 /; 2

x = 7

20.

a) (x+3)(x + 5) = -4(x(do 2) + 2) + 5x(do 2)

x(do 2) + 5x + 3x + 15 = -4x(do2) + -8 + 5x(do 2)

5x + 3x = -8 - 15

8x = - 24 / ;8

x = -3

b) (x - 2)(4 + x) = x(x - 5)

4x + x(do 2) - 8 - 2x = x(do 2) -5x

4x + 2x(do 2) - 7x = 8

-3x + 2x(do 2) = 8

c) - 2x(x+1) = (3 - 2x)(x + 2)

- 2x(do 2) - 2= 3x + 6 - 2x(do 2) - 4x

x = 8

D)

(x - 3)(x + 3) = (x - 2)(do 2)

x(do 2) + 3x -3x - 9 = x(do 2) - 2x - 2x + 4

- 9 = -4x + 4

4x = 13

x = 13/4