SOLUTION: graph the function. f(x) = -2x -5

Question 74204: graph the function.
f(x) = -2x -5

Found 2 solutions by jim_thompson5910, bucky:
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
You can just pick 2 numbers for x and plug them in to get 2 numbers of y (or f(x)). Lets let x=0 and x=1

So our first point is (0,-5). Now lets plot our second point. Lets let x=1

So our second point is (1,-7). Lets plot these points and draw a line between them
Connect the 2 dots to make a line
Now just connect the points with a ruler.
So here's what the graph looks like.
Answer by bucky(2189) (Show Source): You can put this solution on YOUR website!
There are several ways to go about graphing this function. One way is to replace f(x) with y
that you get the equation:
.
y = -2x -5
.
Now all you need to do is to assume values for x and calculate the corresponding values for y.
.
For example, if you let x be zero the equation reduces to:
.
y = 0 - 5 = -5.
.
So a (x,y) point on the graph is (0,-5). Plot it.
.
Then assume another value of x. For example, Let x = 5. Substitute it into the equation and
you get:
.
y = (-2)*(5) - 5 = -10 - 5 = -15.
.
So another (x,y) point on the graph is (5,-15). Plot it also.
.
Try one more. Let x = -5. Substitute that into the equation and you get:
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y = (-2)*(-5) - 5 = 10 -5 = +5.
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So a third (x,y) point is (-5,+5). Plot it.
.
All three points should lie in a straight line. Put a straight edge on them and extend a line
through them. That is the graph.
.
Another way to graph y = -2x - 5 is to recognize that this equation is in the slope-intercept
form of y = mx + b where m, the multiplier of x, is the slope and b is the value at which the
graph crosses the y-axis. Comparing the slope-intercept form with the given equation allows
you to see that m must equal -2 and b must equal -5. This means that the graph crosses the
y-axis at y = -5 and it has a slope of -2. That means that you can put your pencil on
the y-intercept point (on the y-axis at -5) then move your pencil 1 unit horizontally
to the right, stop there, then go vertically down 2 units (the slope is -2 and the minus
sign means move down). When you get there put a dot. That will be a point on the graph.
From that point you can again move to the right 1 horizontal unit then down 2 vertical units
and mark that point. That's a third point on the graph.
.
And when you get done with these two different methods you should find that your graph looks like
this:
.

.
Hope this helps you with graphing slope-intercept type equations.
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