How do you find the equation of a line that goes through (-2,-5) and (4,-3)? Can you show me how?
2006-09-13 15:27:12 · 6 answers · asked by Chris K 6 in Science & Mathematics ➔ Mathematics
(-2,-5) and (4,-3)
m = (-3 - (-5))/(4 - (-2))
m = (2)/(4 + 2)
m = 2/6
m = (1/3)
(-2,-5), m = (1/3)
-5 = (1/3)(-2) + b
-5 = (-2/3) + b
-15 = -2 + 3b
3b = -13
b = (-13/3)
ANS : y = (1/3)x - (13/3)
2006-09-13 17:15:16 · answer #1 · answered by Sherman81 6 · 0⤊ 0⤋
You can also use the point-slope form for the equation which is
y - y1 = m (x - x1) where (x1,y1) is a point on the line and m = slope.
As above, slope = (-3 - -5)/(4 - -2) = 2/6 = 1/3
So either y - -3 = 1/3 (x - 4) or y - -5 = 1/3 (x - -2)
[change the double minuses to +]
2006-09-13 22:40:33 · answer #2 · answered by hayharbr 7 · 0⤊ 0⤋
u have to kno that y=mx+c is linear equation. since u give two points, it can be linear equation, y=mx+c ,where 'm' is slope or gradient(used in calculus) and 'c' means y intercept, that means value of 'y' when x=0,
the gradient equation is m= y2-y1 / x2-x1. if u take ( -2, -5 ) as a first point, y1= -5 and x1= -2.thus, y2= -3 and x2= 4
m= -3 - (-5)/ 4- (-2)
m= 2/6= 1/3
so, y= 1/3x+c
( 4,-3 ) means that y is -3 when x=4
by substituting -3 in y, and 4 in x,
we get, -3= 4/3+c
c= -3-4/3
c=-9/3-4/3
c=-13/3
so equation is y=1/3x-13/3
hope u wil underatand with ease
2006-09-13 23:25:29 · answer #3 · answered by free aung san su kyi forthwith 2 · 0⤊ 0⤋
Okay, you know that the equation for a line is y=mx+b, where m is the slope, and b is the y-intercept. To find the slope, you take the first y value, and subtract the second one from it. Repeat this process for the first and second x values, and then take your difference in y divided by the difference in x, and that is your slope. Once you have your slope, you can plug one of your known ordered pairs into your equation to find the y-intercept. You adjust your b-value in the line equation until the equality makes sense for that ordered pair. You can test that equation out for other ordered pairs to make sure you did it correctly.
2006-09-13 22:36:29 · answer #4 · answered by Josh N 1 · 0⤊ 0⤋
y = mx + b
Find m first.
change in y / change in x
(-3 - -5 ) / (4 - -2) = 2/6 = 1/3
Then find b, using either point.
y = 1/3 x + b
(-3) = 1/3 * (4) + b
-3 = 4/3 + b
-3 - 4/3 = b
b = -13/3
y= 1/3x+ -13/3
2006-09-13 22:35:06 · answer #5 · answered by J G 4 · 0⤊ 0⤋
find ths slope of the line (rise/run)
hint: slope = (y2-y1)/(x2-x1)
the slope of this line should be negative (oops... i was wrong)
y = (slope)x + c
plug in a set of coordinates as (x,y) and solve for c, to get
y=mx + c
2006-09-13 22:30:32 · answer #6 · answered by Anonymous · 1⤊ 0⤋