What are the steps to solve by substitution?


Rivkah Carl, I work at Noodle

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Solving a system of linear equations using substitution may seem confusing. There are a number of different approaches, but here is a guideline for steps to take. Similar to the discussion in the video the key is: 1) Write out the two equations and decide what variable to isolate in your first equation. For example: if you choose "x", then make sure that only "x" is alone on the left side of the equation. Every other number and variable should be on the right of the equation. 2) Then in the second equation- whenever you see an "x", insert with parenthesis, the right side of the first equation. This will be all the numbers and variables (without the "x"). 3) Focus only on the second equation now. Remember to distribute if multiplying with parenthesis. And Isolate the second variable "y". This means only "y" should be alone and y will then equal a number. 4) once you have found the value of "y", plug that number into the "y" spot in the first equation and add/subtract or multiply the numbers in order to find the value of "x".

Good luck!

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