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Question 766500: How do you graph -3x+5y=25
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! 3x + 5y = 25 is a straight line.
since this is a straight line, you only need 2 points to be able to graph it.
pick any 2 values for x and find the corresponding value for y and you have your 2 points.
assume x = 0 gets you y = 5 because -3(0) + 5(5) = 25
assume x = 5 gets you y = 8 because -3(5) + 5(8) = -15 + 40 = 25
you have 2 points:
(x1,y1) = (0,5)
(x2,y2) = (5,8)
plot these 2 points on the graph and then draw a straight line through both of them and you have your graph.
your graph should look like this:
i drew a horizontal line at y = 8 so you can see where the intersection of y = 8 and the line is. draw an imaginary vertical line down from that intersection and you will see that the value of x = 5 when the value of y = 8
to find the slope and the y-intercept of your equation, you can find it from the graph or you can convert your equation to slope intercept form.
start with:
-3x + 5y = 25
add 3x to both sides of the equation to get:
5y = 3x + 25
divide both sides of the equation by 5 to get:
y = (3/5)x + 5
this is the slope intercept form of the equation.
that form is y = mx + b
m is the slope and b is the y-intercept.
in your equation, the slope is (3/5) and the y-intercept is 5.
the y-intercept is the value of y when x is equal to 0.
the slope is the change in the value of y divided by the change in the value of x.
your 2 points are, once again:
(x1,y1) = (0,5)
(x2,y2) = (5,8)
slope will be equal to (8-5) / (5-0) which is equal to 3/5.,
formula for the slope is:
slope = (y2-y1) / (x2-x1)
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