GEOMETRY

MILBY HIGH SCHOOL

MR. SAUCEDO

3.5 Write and GraphEquations of Lines

OBJECTIVE

We will learn how to write equations of a line.

REVIEWX-INTERCEPT & Y-INTERCEPT

SLOPE – INTERCEPT FORM

WRITING AN EQUATION

WE NEED 2 THINGS IN ORDER TO WRITE AN EQUATION IN SLOPE-INTERCEPT FORM.

y = mx + b

Slope (m)&

y-intercept (b).

OBSERVE

Write the equation of a line with slope 3 and y-intercept 6.

m=3b=6.

Plug in m, and b, into the equation: y=mx+b

y=3x+6

CHECKPOINT

Write an equation for the line that has a slope of -3 and a y-intercept of ½.

m=-3b= ½

Plug them in to the formula y=mx+b

y=-3x + ½

GUIDED PROBLEM 1

Write an equation of the line in slope-intercept form.

CHECKPOINT

Find the equation of the line in slope-intercept form.

GUIDED PROBLEM 2

Write an equation of the line passing through the piont (-1,1) that is parallel with the equation y=-2x-3.

CHECK POINT

Write an equation of the line passing through the point (2, -3) that is parallel to the line with the equation y=6x+4.

GUIDED PROBLEM 3

Write an equation of the line passing through the point (2, 3) that is perpendicular to the line with the equation y=-2x+2

CHECK POINT

Write an equation of the line passing through the piont (3,-4) that is perpendicular to the line with the equation y= (-½)x - 1

What if we get an equation in standard form?

Graph 3x + 4y = 12

CLOSING QUESTIONS

What is the formula (or equation) for a line in slope-intercept form?

What steps do we take to write an equation of a line if we are given a graph of a line?

What steps do we take to write an equation of a line if we are given a slope and a point on the line?

INDEPENDENT PRACTICE

ENTER THE FOLLOWING PROBLEMS FROM THE BOOK, PAGE 184.

1.Problem 6, 2.Problem8, 3.Problem 9, 4.Problem 10, 5.Problem 12, 6.Problem 14, 7.Problem 18, 8.Problem 28, 9.Problem 30, 10.Problem 50.

HOMEWORK

WORKBOOK, SECTION 3-5Pages 55-57PROBLEMS: 1, 5, 7, 9, 11, 14, 17,

#25 on separate sheet of paper.