Equations

JessicaCortz

New member
Joined
Jul 17, 2018
Messages
1
Hi I was wondering how to complete these two questions.

Question 1---Given a line with an x-intercept of 9 and a y intercept of -5, write the slope intercept form of the line that shifts the original graph left by 3 and reflects it across the x-axis.

Question 2---Given the equation y=3/8x + 9 , write the slope intercept form of the equation that would shift the original equation right 18 and down 3.

Thank you
 
Last edited by a moderator:
There are different ways to solve exercises like this. Which method does your class use? Do you have any work to show?

Transforming functions is one method. Check out this lesson. For an example, it uses a quadratic function (instead of linear), but the shifting properties are the same for both.

Does any of that information look familiar?

Also, let us know whether you've learned how to write an equation for a line, given the coordinates of two points on the line.

For example, can you write an equation for the line that passes through these points?

(0,5)

(9,0)͏͏͏͏͏͏͏
 
What became of the original problem? Did JessicaCortz just remove the whole thing?

If so, Jessica, please do NOT remove problems. Whether you just decided you were no longer interested or were able to solve the problem, other people here may be interested in the problem.
 
Thanks, mmm444bot

Hi I was wondering how to complete these two questions.
First, the "slope intercept form" of any (non-vertical) line is y= mx+ b.

Question 1---Given a line with an x-intercept of 9 and a y intercept of -5, write the slope intercept form of the line that shifts the original graph left by 3 and reflects it across the x-axis.[/quote]
If we "shift left by 3" then x= 9 is shifted to 9- 3= 6. y= 0 when x= 6: 0= 6m+ b. And the y intercept. (0, -5) is shifted to (-3, -5). -5= -3m+ b. If we subtract the second equation from the first, 0- (-5)= 6m+ b- (-3m+ b) or 5= 9m. m= 5/9 and then 0= 6m+ b= 6(5/9)+ b= 10/3+ b so b= -10/3. y= (5/9)x- 10/3. Multiplying both sides by 9, 9y= 5x- 30 or 5x- 9y= 30. Reflecting across the x-axis changes y to -y: 5x+ 9y= 30.

Question 2---Given the equation y=3/8x + 9 , write the slope intercept form of the equation that would shift the original equation right 18 and down 3.
Shifting right 18 replaces x with x- 18. Shifting down 3 replaces y with y+ 3.
y+ 3= (3/8)(x- 18)+ 9 or y= (3/8)(x- 18)+ 6.

Thank you
 
Top