Z-4/9z=4'9 помогите срочно я тупой

Question

Z-4/9z=4'9 помогите срочно я тупой

Answer 1

Z - 4/9z = 4,9
5/9z = 4/9
z = 4/9 : 5/9
z = 4/5

Answer 2

z-(4/9)z=4.5

4.5=45/10

z(1-4/9)=45/10

5/9z=45/10

z=45/10*9/5=81/10=8.1 

 

или

 

z-4/9z =4.5

(9z-4)/9z=4.5

9z-4=40,5z

z(9-40,5)=4

z=4/(9-40.5)=4/31.5=8/63

Comments

Почему 4'5 там 4'9

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Я тупой

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z - 4/9z=9/2
z (1-4/9)=9/2
z(5/9)=9/2
z= 9/2 * 9/5
z= 81/10 = 8.1

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я просто запуталась

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а не

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z - 4/9z = 4,9
5/9z = 4/9
z = 4/9 : 5/9
z = 4/5

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вот