Question

Determinati numarul necunoscut din fiecare proportie
a)X-2/5=2x-1/13
b)2x+3/x+5=7/4
c)4x-5/3=2x+8/2
d)3x+11/9=x+6/4
e)4/9=3x+1/2x+12
f)3/5x+2=7/2x+15

Answer 1

a)x-2/5=2x-1/13

13 (x-2)=5 (2x-1)

13x-26=10x-5

13x-10x=-26+5

3x=-21

x=-21÷3

x=-7

b)2x+3/x+5=7/4

7 (x+5)=4 (2x+3)

7x+35=8x+12

7x+8×=35-12

-x=23

c)4x-5/3=2x+8/2

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

6x+24=8x-10

6x-8x=24+10

-2x=34

x=34÷(-2)

x=17

d)3x+11/9=x+6/4

4 (3x+11)=9 (x+6)

12x+44=9x+54

12x-9x=44-54

3×=-10

x=(-10)÷3

x=-10/3

×=3,(3)

e)4/9=3x+1/2x+12

4 (2x+12)=9 (3x+1)

8x+48=27x+9

8x-27x=48-9

-19×=39

x=39÷(-19)

x=39/-19

×=−2.0526315789

f)3/5x+2=7/2x+15

3 (2x+15)=7 (5x+2)

6x+45=35x+14

6x-35x=45-14

-29×=31

×=-29/31