# Section 2-4: Writing Linear Equations - PowerPoint PPT Presentation

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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. Slope-Intercept Form. y = ______ [ ____ = mx + b]

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Section 2-4: Writing Linear Equations

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### 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.

### 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 __________

x

y

### Write the equation of the line.

• First (and easiest) b = ?

• b =

• m = ?

• m =

• y =

x

y

• b = ?

• b =

• m = ?

• m =

• y =

x

y

• b = ?

• b =

• m = ?

• m =

• y =

y = -4x + 3

m =

b =

y = 5 - 1/2x

m =

b =

8x + y = 3/4

m =

b =

4x - 2y = 10

m =

b =

y = -1/3x

m =

b =

y = 5

m =

b =

m = -3, b = 1

m = -2/5, b = -4

m = 0, b = 10

m = 1, b = 0

m = 0, b = 0

### 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 _________.

### 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.

### 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 ____.

• ____________

### Write the equation.

• y - 2 = 1(x - 3)

• Simplify.

• ______________

• add two to both sides

• __________

### Give the equation of the line through the points (4, 3) and (7, -2)

• m =

• plug either point.

• y - 3 =

• y =

• y =

### 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 =