Linear Equation Fundamentals

A linear equation is an algebraic equation where variables are only raised to the power of 1. The most common form you'll see is the standard form: Ax + By = C, where A, B, and C are constants.

When working with linear equations, you'll often use the slope-intercept form: y = mx + b. In this form, m represents the slope (how steep the line is), and b is the y-intercept $where the line crosses the y-axis$. This form makes graphing much easier!

The point-slope form $y - y₁ = m(x - x₁)$ comes in handy when you know a point on the line and its slope. To find the slope between two points, use the formula m = $y₂ - y₁$/$x₂ - x₁$. This measures the "rise over run" or vertical change divided by horizontal change.

💡 Think of slope as a "steepness rating" - positive slopes rise as you move right, negative slopes fall, zero slopes are flat, and undefined slopes are vertical lines!

Working with Linear Equations

When graphing linear equations, you only need two points to draw the entire line. Remember that horizontal lines have a slope of 0, while vertical lines have undefined slopes.

Parallel lines have the same slope, while perpendicular lines have slopes that are negative reciprocals of each other $their product equals -1$. This relationship is super useful when solving geometry problems!

When solving linear equations, your goal is to isolate the variable using inverse operations. For example, if you have 3x + 4 = 10, subtract 4 from both sides, then divide by 3 to get x = 2.

Linear inequalities work similarly to equations but use symbols like <, >, ≤, or ≥ instead of equals signs. The key difference when solving them is that you flip the inequality sign when multiplying or dividing by a negative number.

🔑 The slope in a linear equation often represents a real-world rate of change - like speed in a distance-time graph or cost per item in a pricing model!