Linear equations describe relationships between two variables using a straight line. In this lesson, you will learn how to interpret the equation y=a+bx, identify its independent and dependent variables, understand slope and the y-intercept, and use the equation to model real-world costs and earnings.
Here, a and b are constants. The variable x is the independent variable: its value is chosen or observed. The variable y is the dependent variable: its value is determined by the equation and depends on x.
All flashcards
What is the general form of a linear equation with one independent variable?
y=a+bx, where a and b are constants, x is independent, and y depends on x.
What does the slope b represent?
It represents the constant change in y for each one-unit increase in x, and determines the line's direction and steepness.
What does the y-intercept a represent?
It is the value of y when x=0; the graph crosses the y-axis at (0,a).
How can you graph a linear equation?
Substitute several values of x to find corresponding y values, plot the resulting ordered pairs, and draw the straight line through them.
What are the slope and intercept in C=31.50+32h?
The slope is 32 dollars per hour, the added cost for each hour. The intercept is 31.50, the one-time fixed charge.
Quiz questions
Which symbol denotes the dependent variable in y=a+bx?Answer: y
In the equation y=7+4x, what is the slope?Answer: 4
Where does the graph of y=−1+2x cross the y-axis?Answer: At (0,−1)
A service charges a $20 fixed fee plus $12 per hour. Which equation gives total cost C for h hours?Answer: C=20+12h
Does a linear equation relating two variables by itself prove that one variable causes changes in the other?Answer: No; the equation alone does not establish causation.