7a+2b=31;21a-b=58

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x+3y=14

Solution for 7a+2b=31;21a-b=58 system of equations: 


  • /| 7*a+2*b-31 = 0| 21*a-b-58 = 0
  • We try to solve the equation: 7*a+2*b-31 = 0
  • 7*a+2*b-31 = 0 // - 7*a-31
  • 2*b = -(7*a-31) // : 2
  • b = (-(7*a-31))/2
  • b = (31-(7*a))/2
  • We insert the solution into one of the initial equations of our system of equations
  • We get a system of equations:
  • /| 21*a-((31-(7*a))/2)-58 = 0| b = (31-(7*a))/2
  • (-1*(31-7*a))/2+21*a-58 = 0
  • 49/2*a-58-31/2 = 0
  • 49/2*a-147/2 = 0
  • 49/2*a-147/2 = 0 // + 147/2
  • 49/2*a = 147/2 // : 49/2
  • a = 147/2/49/2
  • a = 3
  • We insert the solution into one of the initial equations of our system of equations
  • For b = (31-(7*a))/2: 
  • b = (31-(3*7))/2
  • b = (31-21)/2
  • b = 10/2
  • b = 5
  • We get a system of equations:
  • /| b = 5| a = 3

 

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