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Mathematics 16 Online
OpenStudy (anonymous):

How to solve and graph 3x + 5y ≤ 340 I got x ≤ 0 y ≤ 68 Can you explain how to graph for me?

OpenStudy (anonymous):

how did you end up with a "0y" in the middle?

OpenStudy (anonymous):

I think the question just wants you to graph it, solve it for y, and then graph it. It would be easier to identify its slope and y intercept in that form.

OpenStudy (anonymous):

yes, I agree... you really should get the original inequality 3x + 5y ≤ 340 into a form more like a line equation: y ≤ mx + b

OpenStudy (anonymous):

Can you explain that I ahave no idea how to do it

OpenStudy (anonymous):

Okay, so.... write your inequality as a standard equation. Then subtract 3x from both sides, then divide by 5

OpenStudy (anonymous):

When you get that figured out, and the equation graphed, plug in any point back into the equation. I usually use 0,0.

OpenStudy (anonymous):

Start: 3x + 5y ≤ 340 Next, get the 3x on the right side of the inequality by subtracting 3x from both sides: 3x -3x + 5y ≤ 340 - 3x 5y ≤ 340 - 3x Next, isolate the y term on the left side by dividing both sides by 5. 5y / 5 ≤ (340 - 3x) / 5 y ≤ (340 - 3x) / 5 y ≤ -(3/5)x + 340/5 y ≤ -(3/5)x + 68 Now, you have an inequality where you can plot the line using the slope and y-intercept. This is essentially the same as graphing lines... it's just inequalities

OpenStudy (anonymous):

68 is where the line crossed the y axis, and 3/5 is the slope of the line.

OpenStudy (anonymous):

So how would the graph look ? The line would not be dotted and it would be shaded?

OpenStudy (anonymous):

The line might be dotted, because it is less than or equal to, if it was just less than it might have to be solid. I don't know how the teacher requires it. Then you should shade the bottom part of the line, because every value that is under that line would satisfy the inequality.

OpenStudy (anonymous):

Its required as like a full graph. With the Labeled lines, points of intersection, and axis. I also have to show the shaded solution of the three inequalities and explain what it represents.

OpenStudy (anonymous):

I just need to know how to graph this.

OpenStudy (anonymous):

@LolLashae Where do you get " 3 inequalities" with only 3x + 5y ≤ 340 from your post ???

OpenStudy (anonymous):

Now suppose: 3x + 5y = 340 -> y = ....?

OpenStudy (anonymous):

68 is where the line crossed the y axis, and 3/5 is the slope of the line. I just need to know how to graph that

OpenStudy (anonymous):

Well, you need to draw the line first, then take its region: y ≤ -3x/5 + 68

OpenStudy (anonymous):

So you get intercept point ( 0, 68 ) and ( 5, 65), can you graph the straight line?

OpenStudy (anonymous):

It would be two lines on the graph? I'm sorry graphing is my weak point in math :( I have basically no idea how to do them

OpenStudy (anonymous):

Do you know how to get the point?

OpenStudy (anonymous):

is it with the y2-y1 and x2-x1 thing?

OpenStudy (anonymous):

You have only ONE inequality 3x + 5y ≤ 340, so it yields ONE line!

OpenStudy (anonymous):

ONE line makes from 2 POINTS

OpenStudy (anonymous):

( 0, 68 ) means ( x = 0, y = 68) means the point lies on y axis!

OpenStudy (anonymous):

Then connect its with other point => straight line!

OpenStudy (mathteacher1729):

Probably the easiest way to graph this without a calculator is to take the original inequality let x = 0 , then solve for y, then let y = 0 and solve for x. 3x + 5y ≤ 340 original equation 3x + 5y ≤ 340 let x = 0 3*0 + 5y ≤ 340 5y ≤ 340 divide both sides by 5 y ≤ 340/ 5 y ≤ 68 this means the y-intercept is y = 68 and the graph is shaded BELOW y = 68. 3x + 5y ≤ 340 original equation 3x + 5y ≤ 340 let y = 0 3x + 5*0 ≤ 340 3x ≤ 340 divide both sides by 3 x ≤ 340/3 x ≤ 113.3 repeating Or x ≤ 113 + 1/3 That means your x intercept is 113.3 repeating and the graph is shaded to the LEFT of x = 113.3 repeating. If you go to wolframalpha.com and type 3x+5y<= 340 You'll see exactly that. :)

OpenStudy (anonymous):

Thank you

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