Simultaneous Equations : Theory

• • In simultaneous equations, you usually have to find the values of x and y 
  • However, it can also be other numbers

  
• In simultaneous equations, if we can get one of the letters to have the same coefficient (e.g. x or y) we can then work towards finding the value of this letter, and substitute it into the one of the equations, to find the value of the other letter
• • In simultaneous equations, once we have gotten one of the letters in both equations to have the same coefficient, we either add the equations or takeaway the equations - the main goal is to cancel out the coefficients 
  • If both of the equations have the same sign (e.g. +, + or -, -), we subtract them 
  • If the signs are different (e.g. + , -) we add them 
  • This will leave us with an equation for the other term, that we can use to work out its value

  
• • Once we find the value of x or y in one of the equations, we substitute it into either of the equations
  • You can then rearrange the equation, to find the value of the other term