Section 2-4: Writing Linear Equations

1. Section 2-4: Writing Linear Equations • We have already seen standard form of an equation, but this form isn’t very useful. • We are going to use slope-int. and point-slope form to write equations.

2. Slope-Intercept Form • y = ______ [ ____ = mx + b] • Remember, MOST of the time we will still have ______ in the final equation. • m is the _______ • b is the __________

3. x y Write the equation of the line. • First (and easiest) b = ? • b = • m = ? • m = • y =

4. x y Write the equation of the line. • b = ? • b = • m = ? • m = • y =

5. x y Write the equation of the line. • b = ? • b = • m = ? • m = • y =

6. y = -4x + 3 m = b = y = 5 - 1/2x m = b = 8x + y = 3/4 m = b = 4x - 2y = 10 m = b = Give the slope and y-int. of each equation.

7. y = -1/3x m = b = y = 5 m = b = Give the slope and y-intercept of each line.

8. m = -3, b = 1 m = -2/5, b = -4 m = 0, b = 10 m = 1, b = 0 m = 0, b = 0 Given the slope and y-int., write the equation of the line.

9. Given the graph, write the equation of the line. • To write the equation of a line, we need two pieces of information: ___________ ________________ • You should be able to get these from _________.

10. Point-Slope Form • Use this form if you are given _________, or a __________. (as long as the pt. isn’t b) • ____________________ • (x1, y1) is one of the given points. • Use the points to calculate m.

11. Give the equation of the line. • the line goes through (3, 2) & (5, 4). • m = • choose either point, we’ll use (3, 2). Plug in 3 for ___ & 2 for ____. • ____________

12. Write the equation. • y - 2 = 1(x - 3) • Simplify. • ______________ • add two to both sides • __________

13. Give the equation of the line through the points (4, 3) and (7, -2) • m = • plug either point. • y - 3 = • y = • y =

14. Give the equation of the line with x-int. 3 and y-int 2. • Because we know the y-int. (b), we only need the slope. • m = • y =