


Linear Equations and GraphsLinear EquationsThe linear function y = mx + b can be rewritten in many forms, for example –mx + y = b. This is a special case of the linear equation ax + by = c. The points satisfying a linear equation, no matter which form it is written in, form a line. We consider two cases of the linear equation ax + by = c.
The xintercept is the point at which the line crosses the xaxis. Along the xaxis, y = 0. Solving the linear equation for x when y = 0 gives
and the xintercept is therefore . For example, the slope of the linear equation 3x + 4y = 12 is , the yintercept is and the xintercept is 12/3 = 4. As mentioned before under the topic of the slope, the slope of a vertical
line is undefined. Exercise 8.
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