Write linear equation in functional natation

Hey guys,

could somebody please check if the following is right?

Task: Write the linear equation 4x -9y = -45 in functional notation, and determine the x-and y-intercepts. Show your work using functional notation.

My work:

4x -9y = -45 is

-9y = -4x -45 is

y = -4/-9 x +5 is

f(x) = -4/-9 x +5

The x-intercept is where y=0

0 = -4/-9 x +5

-5 = -4/-9 x

x = -11.25

The y-intercept is where x=0

f(0) = -4/-9 (0) +5

f(0) = 0 +5

f(0) = 5

Is my whole work right or is there any mistake? Thank you.

Re: Write linear equation in functional natation

Quote:

Originally Posted by

**ford2008** Task: Write the linear equation 4x -9y = -45 in functional notation, and determine the x-and y-intercepts. Show your work using functional notation.

$\displaystyle f(x)=\frac{4}{9}x+5$.

Re: Write linear equation in functional natation

Quote:

Originally Posted by

**ford2008** Hey guys,

could somebody please check if the following is right?

Task: Write the linear equation 4x -9y = -45 in functional notation, and determine the x-and y-intercepts. Show your work using functional notation.

My work:

4x -9y = -45 is

-9y = -4x -45 is

y = -4/-9 x +5 is

-4/-9= 4/9 but you seem to recognize that later so it is just awkwardly written, not an error.

Quote:

f(x) = -4/-9 x +5

The x-intercept is where y=0

0 = -4/-9 x +5

-5 = -4/-9 x

x = -11.25

The y-intercept is where x=0

f(0) = -4/-9 (0) +5

f(0) = 0 +5

f(0) = 5

Is my whole work right or is there any mistake? Thank you.

Yes, those are correct.

I realize you were told to "Write the linear equation 4x -9y = -45 in functional notation" but, frankly, it would have been simpler to use the original form.

With 4x -9y = -45, setting y to 0 gives 4x= -45 so that x= -45/4= -11.25 is the x-intercept. Setting x= 0, -9y= -45 so that y= 5 is the y intercept.