First, you solve for the line in y-intercept form:
x - 2y = 24
-2y = -x + 24
y = (1/2) x - 12
So our slope of the line is 1/2. Remember that in order to find the line perpendicular, you have to take the "negative reciprocal" of the slope. In our case, since m = 1/2, the negative reciprocal of the perpendicular line will be m = -2
Thus, our equation is y = -2x + b
Then we use the "slope = slope" method of calculating the line with the given points (1,3), to get
(y - 3)/(x - 1) = -2
y-3 = -2(x-1)
y-3 = -2x + 2
2x + y - 5 = 0 (which is now in standard form)
2006-12-01 09:40:42
·
answer #1
·
answered by Puggy 7
·
0⤊
0⤋
Heres how i would do it:
solve equation for y:
x - 2y = 24
+2y +2y
x = 2y+24
-24 -24
x-24 = 2y
divide both sides by 2... (same thing as multiplying both sides by (1/2) )
(1/2)x - 12 = y
perpendicular means that if the line has the slope is (a/b), the slope of the line perpendicular to the first line is -(b/a).
Therefore:
original slope = (1/2) so
perpendicular slope = -(2/1) or just -2
so far, your equation is y = -2x+b (b = y-intercept)
to find y-intercept:
plug in the point (1,3) for x and y in the equation
3 = -2(1) + b
3 = -2 +b
+2 +2
5 = b
so in slope intercept the equation is y = -2x+5
NOW to put it in standard form:
y = -2x+5
+2x +2x
2x + y = 5
and you are finished!!!!!!!!!
2006-12-01 17:47:32
·
answer #2
·
answered by nanabanana 2
·
0⤊
0⤋
A perpendicular line has a negative reciprocal slope. This means in perpendicular lines, m * n = -1 where m is the slope of one line and n is the slope of the other. The slope is easily discernible in y = mx + b form (in which m is the slope). So first manipulate this equation a bit.
x - 2y = 24
::subtract an x from both sides
-2y = -x + 24
::divide by -2
y = 1/2x - 12
From this, we can see that the slope of this line is 1/2. The negative reciprocal of 1/2 is -2. Then, we write an equation using this slope and the point given. We utilise point-slope form in this instance.
y - y of point = m (x - x of point)
y-3 = -2 ( x-1)
::change into standard form
y-3 = -2x +2
y+2x=2+3
2x + y = 5 is your answer.
2006-12-01 17:44:43
·
answer #3
·
answered by Lucan 3
·
0⤊
0⤋
First, find the gradient of that line: 2y = x-24, so y = 0.5x - 12, so the gradient is 0.5.
Thus the gradient of a perpendicular line is -1/0.5 = -2.
So the line is of the form y = -2x + c
Substitute in the point to get 3 = -2 + c, so c = 5, and the equation is y = -2x + 5.
Or 2x + y = 5.
2006-12-01 17:39:14
·
answer #4
·
answered by stephen m 4
·
0⤊
0⤋
To get the necessary negative reciprocal slope, reverse the x and y coefficients and the sign between, getting 2x + y = ....
and then plug in the point. 2(1)+3 = 5.
So 2x + y = 5.
2006-12-01 17:38:56
·
answer #5
·
answered by Philo 7
·
0⤊
0⤋
x-2y=24
-2y=-x+24
y=x/2-12
slope is 1/2
slope of perpindicular is -2
y=-2x+b
3=-2+b
b=5
y=-2x+5
2x+y=5
2006-12-01 18:04:49
·
answer #6
·
answered by yupchagee 7
·
0⤊
0⤋