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8R Math Vocabulary # 4 (Graphing Linear Equations).notebook
1
Ahrens
GRAPHING LINEAR EQUATIONS
8th Grade Math Vocabulary
Graphing Linear Equations
Coordinate Plane
Coordinate Plane
The two dimensional plane or flat surface that is created when the xaxis intersects with the yaxis.
a.k.a.
Coordinate Graphor
Cartesian Plane
Plot lines and points!
Geometry Theorem
Geometry Theorem
Through any two points in a plane there can be drawn only one line.
Grade
GradeA unit engineers use to measure the
steepness of a hill.
10 feet
25 meters
3 meters
5 feet
25.
5
3
10= 2 grade of
hill is 2.
grade of hill is
The sign warns cars the hill has a grade of 7.
Origin
(0,0)
OriginThe point where zero on the xaxis
intersects zero on the yaxis. The point
(0,0).
Used to
graph
coordinates!
(4,3)
right 4 from origin
down 3 from origin
Quadrant
Quadrant Any of the four regions created when the xaxis intersects the yaxis that are usually numbered
with Roman numerals.
II I
III IV
"First Quadrant"
8R Math Vocabulary # 4 (Graphing Linear Equations).notebook
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xaxis
Xaxis Horizontal number line that extends
indefinitely in both directions from zero.
( a , b )
"xcoordinate" (distance away from origin on xaxis)
xintercept
xintercept
Where a line crosses the xaxis.
None!
(2,0)
(4,0)
yaxis
YaxisVertical number line that extends
indefinitely in both directions from zero.
( a , b )
"ycoordinate" (distance away from origin on yaxis)
yintercept
yintercept
Where a line crosses the y axis.
(0,6)
(0,4) y = mx + b
"b" = yintercept (where it crosses the yaxis)
(0,b)
Linear Equation
Linear Equation
Any equation whose graph is a line.
y = mx + bwhere "b" is the line's yintercept and "m" is its
slope.
slope intercept form:
point slope form:
y y1 = m(x x1)where "(x1,y1)" is a point on the line and "m" is its
slope.
standard form:
ax + by = cwhere a is nonnegative and a and b cannot both be 0.
Slope
SlopeHow much a line rises or falls
y = mx + b
"m" = slope
Steepness of a line
The ratio of a line's rise over its run
"Steepness" and "Position" of a Lineformula for slope: m = y2 y1
x2 x1
8R Math Vocabulary # 4 (Graphing Linear Equations).notebook
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Proportional Relationship
Proportional Relationship
When two quantities have the same relative size.
24
12
if weight is proportional to age, then a weight of 3kg on the 1st day means it will weigh 6kg on the 2nd day, 9kg on the 3rd day, 30kg on the 10th day, etc.
Table of Values
Table of Values
Numbers or quantities arranged in rows and columns.
rows
columns
0
321
1613107
0
321
x y3(x)+7 (x,y)
1613107
3(3)+73(2)+73(1)+73(0)+7
(3,16)(2,13)(1,10)(0,7)x y
System
SystemTwo or more linear equations working together.
y = 2x 3y = x 1 3x + y = 11
x 2y = 6
2x + y = 3x 2y = 4
System Solution
System Solution
An ordered pair that will work in each equation.
3x + y = 11x 2y = 6
system
solution
x = 6 + 2y3(6 + 2y) = 1118 + 6y = 11
6y = 7y = 7 6
x = 6 + 2(7/6)x = 3 7/10
(7/6, 3 7/10)
Parallel
ParallelTwo lines that have the same slope and never interesent.
Perpendicular
Perpendicular
Two lines that interset and form a right angle.
RightAngle
8R Math Vocabulary # 4 (Graphing Linear Equations).notebook
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Substitution
Substitution
The process of putting in a value in place of another.
y = 24 4x 2x 3(24 4x) = 22x 72 + 12x = 2
14x = 70x = 5
y = 4
2x 3y = 24x + y = 24 2x 3y = 2
System: Solution: (5,4)
Check:2(5) 3(4) = 2
y = 24 4(5)
10 12 = 2 2 = 2
4(5) + (4) = 24 20 + 4 = 24
24 = 24
Elimination
EliminationThe process of eliminating one of the variables in a system of equations.
2x 3y = 24x + y = 24
System:
Eliminate the y variable
2x 3y = 24x + y = 24(3)( ) (3)
2x 3y = 212x + 3y = 72( )+14x = 70 x = 5
2(5) 3y = 2 10 3y = 2
3y = 12 y = 4
Solution: (5,4)