View Full Version : Graphing

Petenerd

06-10-2009, 11:38 PM

How can you graph this? Can you give me an equation like y = \frac 2 3x + 6?

1. The line having slope -3 and containing the point (-6,5)

2. The line having slope \frac 2 3 and containing hte point (0,4)

Aladdin

06-11-2009, 03:42 AM

To graph Linear equation: You should find two points (knowing that a line consist of several points).

y= = 2/3x + 6

let x=0 >>y=6 >>First point (0,6)

let x=3 >> y=8 >>Second point (3,8)

Locate those two points and join them (it's a line not a segment)

Edit

Sorry, I didnt read the questions 1 & 2

Subhotosh Khan

06-11-2009, 06:47 AM

How can you graph this? Can you give me an equation like y = \frac 2 3x + 6?

1. The line having slope -3 and containing the point (-6,5)

2. The line having slope \frac 2 3 and containing hte point (0,4)

There are standard equations for this type of problems - studying the textbook would help.

If a line has a slope 'm' and passes through a point (x[sub:fm9k0els]1[/sub:fm9k0els], y[sub:fm9k0els]1[/sub:fm9k0els]), then the equation of the line is:

y - y[sub:fm9k0els]1[/sub:fm9k0els] = m * (x - x[sub:fm9k0els]1[/sub:fm9k0els])

sandman369

06-12-2009, 04:39 AM

How can you graph this? Can you give me an equation like y = \frac 2 3x + 6?

1. The line having slope -3 and containing the point (-6,5)

2. The line having slope \frac 2 3 and containing hte point (0,4)

They give you the slope and a point in each case. To graph a line in this situation, you can either find the equation first, or plot another point first.

To plot another point: In question #1, your given point is (-6,5) and slope is -3. Slope means rise over run or y/x. So this means for every 1 unit to the right (along x), you move 3 units down (along y). So from (-6,5) your next point would be (-5,2) [when you add 1 to x-value, you subtract 3 from y-value].

To find the equation: they seem to be asking for the y = mx + b form of a linear equation, where m is the slope and b is the y-intercept. Since they are giving you the slope (m), and a point (x- and y-value), all you need to do is plug in those values to find b, and write the equation as y = (number)x + (number)

If you find the equation before graphing, then all you need to do is plug in a value for x, which will give you a y-value, plot that point, then repeat with a different x-value.

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