Question

va rog frumos imi dau toate punctele!

Answer 1

Răspuns:

Explicație pas cu pas:

4.

a/4=7/2b

2b*a = 4*7

2b*a = 28

b*a = 28 : 2 = 14

a^2*b^2 = (a*b)^2 = 14^2 = 196

3ab = 3*14 = 42

196 - 42 + 5 = 159

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6.

x/21 = 2/3

x = 21*2/3 = 14

y/6 = 2/3

y = 6*2/3 = 4

z/9 = 2/3

z = 9*2/3 = 6

1/2*14 + 3/4*4 + 2*6 = 7 + 3 + 12 = 22

___________

7.

x/2 = y/3 = z/4 = k

x = 2k

y = 3k

z = 4k

2x + y + 5z = 81

4k + 3k + 20k = 81

27k = 81

k = 81 : 27 = 3

x = 2*3 = 6

y = 3*3 = 9

z = 4*3 = 12

E = 3x - y + 2z = 3*6 - 9 + 2*12 = 18 - 9 + 24 = 33