Question

Na dzisiaj !!!!!!!!!

Oblicz i sprawdź .

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

3 x - ( 7 + x ) = 3 x

x + ( x - 4 )= x + 7

23 + 5 x = 23

7 x - ( x + 3 ) = 21 - ( x - 3 )

Daję naj i 20 pkt. :) Ma być dobrze !

Answer 1

a)
3x - ( 8 - x ) = 2 + 3x
3x - 8 + x = 2 + 3x
3x + x - 3x = 2 + 8
x = 10

Sprawdzenie:
L = 3*10 - (8-10) = 32
P = 2 + 3*10 = 32

b)
3x - ( 7 + x ) = 3x
3x - 7 - x = 3x
3x - x - 3x = 7
-x = 7     /:(-1)
x = -7

Sprawdzenie:
L = 3(-7) - (7+(-7)) = -21
P = 3(-7) = -21

c)
x + ( x - 4 )= x + 7
x + x - 4 = x + 7
x + x - x = 7 + 4
x = 11

Sprawdzenie:
L = 11 + (11-4) = 18
P = 11 + 7 = 18

d)
23 + 5x = 23
5x = 23 - 23
5x = 0   /:5
x = 0

Sprawdzenie:
L = 23 + 5*0 = 23
P = 23

e)
7x - ( x + 3 ) = 21 - ( x - 3 )
7x - x - 3 = 21 - x + 3
7x - x + x = 21 + 3 + 3
7x = 27    /:7
x = 27/7

Sprawdzenie:
L = 7*27/7 - 27/7 - 3 = 189/7 - 27/7 - 3/1 = 162/7 - 21/7 = 141/7
P = 21 - 27/7 + 3 = 21/1 - 27/7 + 3/1 = 147/7 - 27/7 + 21/7 = 120/7 + 21/7 = 141/7