Vähennystapa

Vähennystapa, often translated as the "subtraction method," is a technique used in solving systems of linear equations. It involves eliminating one of the variables by subtracting one equation from another. The goal is to manipulate the equations so that when one is subtracted from the other, the coefficients of one variable are opposites or identical, allowing it to cancel out.

To apply the vähennystapa, one typically aligns the equations so that like terms are in the same columns. If the coefficients of the variable to be eliminated are not the same or opposites, one or both equations may need to be multiplied by a constant to achieve this. Once the coefficients match or are opposite, the equations are subtracted (or added, if the coefficients are opposite). This results in a new equation with only one variable, which can then be solved.

After finding the value of the first variable, this value is substituted back into one of the original equations. This allows for the calculation of the second variable. The vähennystapa is a fundamental method for solving systems of equations and is often taught alongside the substitution method. It is particularly useful when the coefficients of one variable are already the same or differ only in sign.