Mathematics for IGCSE & O level - Equations (Section 3 - No. 27)
In a system of equations, if the coefficients of a variable are the same but with opposite signs, what is the most efficient method to eliminate that variable?
Subtract the equations.
Multiply one equation by -1.
Add the equations.
Substitute.
คำอธิบาย
Adding the equations directly eliminates the variable.