its for aalgebra..and i have to make an equation of a line...or some thing like that..and it really sucks :)
2007-06-07 09:42:17 · 8 answers · asked by diana 2 in Science & Mathematics ➔ Mathematics
A straight line of gradient m and with intercept c on the y axis has the equation:
y = mx + c.
2007-06-07 09:50:29 · answer #1 · answered by Anonymous · 0⤊ 1⤋
I use y= mx +b (where m is the slope and b is the y-intercept)
You can find m (the slope of the line) if you are given 2 points on the line (x1, y1) and (x2, y2).
The formula for finding the slope is (y2-y1)/(x2-x1).
For example if you are given the points (1, 2) and (2, 3), the slope = 3-2/2-1 = 1/1 = 1.
You can also find the equation for a line if given the slope (m) and a point on the line. For example, say you are given a line with a slope of 2 and a point (2, 4) which lies on the line.
Then you know y = 2x +b but you still have to find b. To find b use the point you know to plug in for x and y. In this example plug in 2 for x and 4 for y.
4 = 2*2 + b
4 = 4 + b
0= b
Therefore the equation for the line is y= 2x + 0 or just y=2x.
Hope that helps!
2007-06-07 10:00:21 · answer #2 · answered by weee_1120 1 · 0⤊ 0⤋
If you are given a point on the line and the slope of the line, it's easy. Simply fill in the fomula y - y1 = m(x - x1.) So, if a point on the line was (3,5) and the slope of the line was 4:
y - 5 = 4(x - 3)
y - 5 = 4x - 12
0 = 4x - y - 7 is the equation of this line.
Sometimes, you will need to do a bit of working out before you can find the slope of the line, for example you might be told that a line is perpendicular to the line you need to get the slope of. In this instance, you will need to find the slope of the perpendicular line and invert it and change the sign to get the slope of the line you need.
Hope I helped! If you're still confused, IM me or something!
2007-06-07 09:49:55 · answer #3 · answered by Buttons 3 · 0⤊ 0⤋
The formula for a line is y=mx+b (not ax), where m is the slope and b is the y-intercept. The slope can be found using the formula, m=(Y2-Y1)/(X2-X1) and the y-intercept can be calculated by substituting X with 0 (zero).
2007-06-07 09:51:16 · answer #4 · answered by Amphibolite 7 · 0⤊ 0⤋
the equation for a line on a graph is usually denoted by the formula
y=mx+c
where
m is the gradient of the line
x is the value of x obviously
and c is the gap between 0 and wherever the line passes the y axis
2007-06-07 09:48:12 · answer #5 · answered by Anonymous · 0⤊ 1⤋
Thats wrong guys ... She's askin for an equation of a line. A constant line! y=k ... Where k is constant
Y= ax + b is a partial variation relation
2007-06-07 09:50:32 · answer #6 · answered by double_drago 3 · 0⤊ 1⤋
y=mx+b
m=slope
b= y intercept
2007-06-07 09:48:18 · answer #7 · answered by amorudence 3 · 3⤊ 0⤋
y = ax + b
2007-06-07 09:45:09 · answer #8 · answered by muhamed a 4 · 0⤊ 1⤋