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How to solve simultaneous equations (substitution method) 連立方程式の解き方(代入法)

Question: Let's solve the following equations by the substitution method. 

① 3x+2y=-2          ② x-4y=18

How to solve: As with the addition and subtraction method, the substition method also solves simltaneous equations by erasing a single letter. In the substition method, bu substituting one equation into the other, a letter is erased.

For this problem, if we reaarange ②, it becomes x=4y+18 ---③. Substituting ③ into equation ①, y =-4. Then, x=2.