Question

determimati x asfel incat fiecare din urmatoarele fractii sa fie egale cu fractia 3/7:
a)x/28
b)45/x
c)2x+1/21
d)51/38+x la puterea a 2
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Answer 1

Răspuns:

3/7=x/28

7x=3×28

x=84:7

x=12

__________

3/7=45/x

3x=7×45

x=315:3

x=105

_______

3/7=(2x+1)/21

7(2x+1)=3·21

14x+7=63

14x=63-7

x=58:14

x=4

_______

3/7=51/(38+x²)

3(38+x²)=7×51

114+3x²=357

3x²=357-114

x²=243:3

x²=81=>x=9