Which equation is in standard form for a linear equation?

• A. y = mx + b
• B. x^2 + y^2 = C
• C. Ax + By = C
• D. A + Bx = Cy

Answer: (C)

Standard form for a linear equation is Ax + By = C, where x and y appear with coefficients on one side and a single constant on the other side (A, B, C are constants, often integers).

Among the options, the one that already fits this pattern has both x and y terms on one side with a single constant on the other side. The first option is written in slope-intercept form, y = mx + b, which is not standard form. The second option has squared terms, x^2 + y^2 = C, so it isn’t a linear equation at all. The fourth option includes a constant term on the left, A, which means it isn’t in standard form as written; it could be rearranged to Bx − Cy = −A and then be in standard form, but as presented it isn’t.

So the form that matches Ax + By = C is the one that expresses a linear equation with x and y terms on one side and a constant on the other.