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Linear equation systems

Solve a pair of linear equations with a simple equation substitution

This math skill teaches solving a pair of linear equations by substituting one equation into another to isolate and solve for a variable. This involves keeping expressions in brackets to maintain correct operation order and simplifying to find the value of the variable.

Learn linear equation systems

Teaching Transcript

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Solve for 'X' in this linear equation by substituting the second equation into the first

We have 2 'Y' in the first equation, and the second equation tells us what 'Y' is, so we can make that substitution. Since 2 is multiplied by all of 'Y', we need to keep it in brackets so we multiply everything we've substituted.

Negative 2 times 2 'X' gives us minus 4 'X' and negative 2 times minus 5 gives us plus 10

Now we can isolate all the variables on the left and the numbers on the right

So 'X' is 7.

Skill Practice

Solve a pair of linear equations with a simple equation substitution

Test your understanding of linear equation systems by practicing it! Work through the below exercises to use it in practice.