SOLUTION: Find the x and y intercepts. Write each one as an ordered pair, then graph. 1. -x + 3y = 9 2. 2x + 5y = -20 Please show me how to do these problems, so I can help my s

Algebra ->  Coordinate-system -> SOLUTION: Find the x and y intercepts. Write each one as an ordered pair, then graph. 1. -x + 3y = 9 2. 2x + 5y = -20 Please show me how to do these problems, so I can help my s      Log On


   

Question 273581: Find the x and y intercepts. Write each one as an ordered pair, then graph.
1. -x + 3y = 9


2. 2x + 5y = -20
Please show me how to do these problems, so I can help my son when he gets up before he goes to school. I just came home from work and found out he didn't understand this.
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
the y intercept is the value of y when x = 0.

the x intercept is the value of x when y = 0

first equation is:

-x + 3y = 9

make x = 0 and this equation becomes 3y = 9 which makes y = 3

make y = 0 and this equation becomes -x = 9 which makes x = -9

the ordered pairs from this would be:

(0,3) for the y intercept.
(-9,0) for the x intercept.

to graph this equation, solve for y to get:

y = (1/3)*x + 3

graph looks like this:

graph+%28600%2C600%2C-15%2C10%2C-5%2C15%2C%281%2F3%29%2Ax+%2B+3%29

second equation is:

2x + 5y = -20

y intercept is the value of y when x = 0

make x = 0 and the equation becomes 5y = -20

solve for y to get y = -4.

x intercept is the value of x when y = 0

make y = 0 and the equation becomes 2x = -20

solve for x to get x = -10

the ordered pairs from this would be:

(0,-4) equals the y intercept (value of y when x = 0)
(-10,0) equals the x intercept (value of x when y = 0)

to graph this equation, solve for y to get

y = (-2/5)*x - 4

graph of this equation looks like this:

graph%28600%2C600%2C-15%2C10%2C-15%2C5%2C%28-2%2F5%29%2Ax+-+4%29

you graph the equations manually by plotting the two points you created on graph paper and then drawing a straight line between them.