Linear Functions
Review
If y is proportional to x ,
then
When express y in terms of x
, y = ?
If y is inversely proportional to x ,
then
When express y in terms of x
, y = ?
Review
Coordinates
P(2,3)
X coordinate and Y coordinate
Q (5, -4) R (-2,3)
Graphing proportion and inverse proportion
Linear Functions
What is a linear function?
It’s a function that can be represented as
and are constants and
How do we determine whether a function is linear or nonlinear?
o A linear equation in two variables, x and y, is an equation that can be
written in the form , where a and b are constants (just numbers).
o Likewise, a linear function is a function whose graph is a non-vertical line.
o A linear function has a constant rate of change and can be represented by a
linear equation in two variables.
o A nonlinear function does not have a constant rate of change and its graph is
not a line.
o If you let be the total cost of a 40-yen bottle filled with grams of a drug
costing 8-yen per gram, then
(Total cost) = (Cost of drug) + (Cost of bottle),
o It takes seconds to run 400m at a speed of metres per second
Time =
Examples
o In the rectangle on the right, Point P moves from B to C on side BC. Letting
cm be the length of segment BP and cm2
be the area of the DPC
1. in terms of
2. Is a linear function of ?
3. Find value for y when = 0 and value of when = 12
4. Domain of x and domain of y (when point P is at vertices B and C)
Examples
Does the table represent a linear or nonlinear function?
A linear function has a constant rate of change
As x increases by 3, y decreases by 6.
The rate of change is constant for both
x and y.
The function is linear.
x 3 6 9 12
y 36 30 24 18
+3 +3 +3
-6 -6 -6
Does the table represent a linear or nonlinear function?
A linear function has a constant rate of change
As x increases by 2, y increases by
different amounts.
The rate of change is not constant for
both x and y.
The function is nonlinear.
x 1 3 5 7
y 2 9 20 35
+2 +2 +2
+7 +11 +15
o When the x value goes from 2 to 8 in the linear function , find increase in ,
increase in and the rate of change,
Increase in is 8 – 2 = 6
Increase in
Rate of change is
Examples
Does the graph represent a linear or nonlinear function? Explain.
The function is linear.
Because the graph is a
line.
The function is nonlinear.
Because the graph is not
a line.
Which of the following equations represent linear functions? Explain.
A linear function can be written in the form , where m and b are constants (just
numbers).
You cannot rewrite the equations , , , and in the form .
So these equations cannot represent linear functions.
You can rewrite the equation as
You can rewrite the equation as
So these equations represent linear functions.
, , , , , and
Does the equation represent a linear or nonlinear function? Explain.
A linear function can be written in the form .
You can rewrite the
equation as
Equation represents a
linear function.
You can rewrite the
equation as
Equation represents a
linear function.
You cannot rewrite the
equation as
Equation is a nonlinear
function.
Graphs of proportion & linear functions
The graph of a linear function is a straight line formed by translating the graph
of by the amount in the +ve direction along the y-axis.
𝑦 =2 𝑥+ 3
For the linear function , complete the table.
Substitute each x and y value in the eqn using values.
𝑦
=
2
𝑥
+
3
3
The graph of the linear function is a st line with a slope of a and b.
The slope is equal to
Y intercept is equal to
the constant -3.

Linear Functions.pptx Explanation of linear function

  • 1.
  • 2.
    Review If y isproportional to x , then When express y in terms of x , y = ? If y is inversely proportional to x , then When express y in terms of x , y = ?
  • 3.
    Review Coordinates P(2,3) X coordinate andY coordinate Q (5, -4) R (-2,3) Graphing proportion and inverse proportion
  • 4.
    Linear Functions What isa linear function? It’s a function that can be represented as and are constants and How do we determine whether a function is linear or nonlinear?
  • 5.
    o A linearequation in two variables, x and y, is an equation that can be written in the form , where a and b are constants (just numbers). o Likewise, a linear function is a function whose graph is a non-vertical line. o A linear function has a constant rate of change and can be represented by a linear equation in two variables. o A nonlinear function does not have a constant rate of change and its graph is not a line.
  • 6.
    o If youlet be the total cost of a 40-yen bottle filled with grams of a drug costing 8-yen per gram, then (Total cost) = (Cost of drug) + (Cost of bottle), o It takes seconds to run 400m at a speed of metres per second Time = Examples
  • 7.
    o In therectangle on the right, Point P moves from B to C on side BC. Letting cm be the length of segment BP and cm2 be the area of the DPC 1. in terms of 2. Is a linear function of ? 3. Find value for y when = 0 and value of when = 12 4. Domain of x and domain of y (when point P is at vertices B and C) Examples
  • 8.
    Does the tablerepresent a linear or nonlinear function? A linear function has a constant rate of change As x increases by 3, y decreases by 6. The rate of change is constant for both x and y. The function is linear. x 3 6 9 12 y 36 30 24 18 +3 +3 +3 -6 -6 -6
  • 9.
    Does the tablerepresent a linear or nonlinear function? A linear function has a constant rate of change As x increases by 2, y increases by different amounts. The rate of change is not constant for both x and y. The function is nonlinear. x 1 3 5 7 y 2 9 20 35 +2 +2 +2 +7 +11 +15
  • 10.
    o When thex value goes from 2 to 8 in the linear function , find increase in , increase in and the rate of change, Increase in is 8 – 2 = 6 Increase in Rate of change is Examples
  • 11.
    Does the graphrepresent a linear or nonlinear function? Explain. The function is linear. Because the graph is a line. The function is nonlinear. Because the graph is not a line.
  • 12.
    Which of thefollowing equations represent linear functions? Explain. A linear function can be written in the form , where m and b are constants (just numbers). You cannot rewrite the equations , , , and in the form . So these equations cannot represent linear functions. You can rewrite the equation as You can rewrite the equation as So these equations represent linear functions. , , , , , and
  • 13.
    Does the equationrepresent a linear or nonlinear function? Explain. A linear function can be written in the form . You can rewrite the equation as Equation represents a linear function. You can rewrite the equation as Equation represents a linear function. You cannot rewrite the equation as Equation is a nonlinear function.
  • 14.
    Graphs of proportion& linear functions The graph of a linear function is a straight line formed by translating the graph of by the amount in the +ve direction along the y-axis. 𝑦 =2 𝑥+ 3
  • 15.
    For the linearfunction , complete the table. Substitute each x and y value in the eqn using values. 𝑦 = 2 𝑥 + 3 3
  • 16.
    The graph ofthe linear function is a st line with a slope of a and b. The slope is equal to Y intercept is equal to the constant -3.

Editor's Notes

  • #3 y=ax is a straight line passing through the origin and point (1, -2) y=6/x is a hyperbola
  • #4 Y = ax is proportional. That is also linear function when This is a linear relationship and function.
  • #7 To answer these questions, let's define the situation clearly. We have a rectangle where Point P moves along side BC from B to C. BP = x cm represents the position of P along BC. yyy is the area of △DPC\triangle DPC△DPC (a right triangle). Area=1/2​×base×height