Problem 3
Solve for y
3x + y = 2
y = -3x + 2
Plug in x = 0
y = -3x + 2
y = -3(0) + 2
y = 2
So the point (0,2) is on the graph. This is the y intercept. This is where the graph crosses the vertical y axis
Plug in x = 1
y = -3x + 2
y = -3(1) + 2
y = -1
The point (1,-1) is also on the line
Plot the two points (0,2) and (1,-1). Draw a straight line through them. Extend this line as much as possible.
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Problem 4
This graph is a horizontal line through -2 on the y axis. Two points on this line are (0,-2) and (1,-2)
Every point on this line has a y coordinate of -2 as y = -2 implies. The x value can be any number you want.
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Problem 5
They key phrase is "you can order as much concrete as you need", so you can order whole numbers or fractions of values depending on how much you want. So this means decimals can be included as well. The value of x can be any positive real number. This function is continuous.
Note: if it said something like "you can only order whole number amounts of concrete" then it would be discrete as something like x = 2.5 isn't allowed
To make a table, you'll plug in various x values to find the corresponding y value. For instance, if x = 0, then
y = 9*x+20
y = 9*0+20
y = 20
indicating that even if you don't order any concrete, you still have to pay $20 for the set up fee
If you order 1 cubic yard of concrete, then x = 1 and y is...
y = 9*x+20
y = 9*1+20
y = 29
So you now pay $29 which is basically the initial $20 fee plus $9 extra for that cubic yard of concrete
Other x,y pairs are...
x = 2, y = 38
x = 3, y = 47
x = 4, y = 56
and so on. They are found in similar ways that the other points were found.