If a,b,and r are real numbers (and if a and b are not both equal to 0) then ax+by=r is called a linear equation in two variables. (The “two varaibles”are the x and they.)The numbers a and b are called the coefficientsof the equation ax+by=r.The number r is called the constant of the equation ax+by=r.
Examples.10x−3y=5and−2x−4y= 7 are linear equations in two variables
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