Functions and lines - Linear funcations

18 important questions on Functions and lines - Linear funcations

Give an equation , we can find an equivalent equation

1. Adding or subtracting the same quantity from both sides
2. Multiplying or dividing both sides by the same nonzero quantity

Linear equations in two variables

A linear equation in two variables is an equation that can be written  Ax+By=c

where A, B, and C are constants and A and B are not both 0.

A soluation to a linear equation in two variables

Is an ordered pair of numbers that satisfy the equation.

the solution set is the set of all solutions of the equation.
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Graph of linear equation

Vertical line and horizontal line

Horizontal and vertical lines

Y=o
x=0

How to sketch the graph

Find first the x and y ints  then you can draw the graph from there

Find the slope that passes through the points (-3,1) and (3,-5) ?

Example

What is the rate of change of the population?

A city is experiencing a decline in population. In 2010, the population was 150,000. By 2020, only 135,00 people lived in the city. Assuming the population decreased linearly, what is the rate of change of the population between 2010 and 2020?

Sketch graph based on standard form/ slope intercept form y=3x-2

  • Y intercepts are  (0,-2)
  • slope 3
  • 3-2 = 1

Find the equation of the line passing through (-1,3) and (2,1)

  • Find first m
  • write the points and m in point-slope form
  • then re-write in standard in standard form
or
  • find first m
  • write in standard form and find b

Linear equation application in business

A company that produces widgets has fixed costs of $200 per day. The total costs are $ 2825 at a producatio level of 75 widgets per day.
Assume that daily total cost c is linearly related to daily production level x.

1. Find the equation realting to cost of production of the form  C=mx+b
2. If production increases to 80 widgets per day, what will the total cost of production per day be ?

A comapny plans to begin manfcaturing a new model of hairdryer. In order to do this, they must first purchase $20,000 of new equipment. Afterwards, the cost of producing each hairdryer ( supplies and labour) is $ 17.

Find a formula for the total cost C(x0 of producing x hairdryers.
What is the total cost of producing 125 hairdryers ?

Slon

Parallel and perpendicular lines

Paralle when both m -2=-2
pependicular -2 = 1/2 

Find the equation of line perpendicular to y=3/2-3 passing through the point (6,1)

M=-2/3
y-1=-2/3(x-6)
y-1=-2/3x+4
y=-2/3x+5

Find the point of intersecation of the lines y=4x-1 and y=11-2x

1. 4x-1=11-2x
       6x=12
        x=2
2. Y=4x-1
       = 4(2)-1
       = 7
3.(2,7)     

Rember : if we multiplay or dvide by number, then we must reverse the inequality.

Example

Interval notation and inequality

  • Interval notation

A golf course charges $52 for a round of golf using a set of their clubs, and $ 44 if you have your own clubs. If a set of clubs cost $270, how many rounds of golf must you play in order to make it more cost-effective to buy your own clubs?

Slon

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