how do you know how to write the equation of the line through point (3,2) and parallel to a line with slope 2?
2006-06-28 08:06:48 · 6 answers · asked by Anonymous in Education & Reference ➔ Homework Help
what if i need an equation of the line through points (-3,2) and (-4,5)?
2006-06-28 08:18:28 · update #1
y=mx+b
2=2(3)+b..... (in this you know the slope is 2 b/c the line is parallel.
2=6+b
-4=b...... (so now you will want to write your equation for your line)
y=2x-4..... (DONE!)
2006-06-28 08:13:32 · answer #1 · answered by Anonymous · 0⤊ 0⤋
y=mx+b is the equation, 3 substitutes x. 2 substitutes y. and the slope 2 is m so:
2=2(3)+b
2=6+b
-4=b
then u subsitute the b and m only in the original equation,so:
y=2x-4
cool, huh?
to find the other one:
(-3,2) (-4,5)
-3=x1 and 2=y1, -4=x2 and 5=y2
so:
y2-y1 over x2-x1
so:
5-2/-4 - -3
3/-4+3
3/-1
=-3, which is the slope...
so:
u choose any coordinate, i chose (-3,2)
2= -3(-3)+b
2= -9+b
add 9 to both sides
11=b
so:
y= -3x+11, i think
2006-06-28 15:19:50 · answer #2 · answered by Pink Panther 1 · 0⤊ 0⤋
Parallel lines have equal slopes, so the slope of the line you are trying to find is 2. Now, go back to slope intercept form (y=mx+b). The y is always y and the x is always x, but you need numbers for m and b. You already have the m, it is 2, the slope. You need to find the b, which is the y-intercept. You are given one x and one y that lie on the line you are trying to find, so substitute them into the slope intercept form and solve for b.
2=2*3+b
2=6+b
-4=b
Your equation is: y=2x-4.
2006-06-28 15:11:26 · answer #3 · answered by houndgirl44 2 · 0⤊ 0⤋
Slope intercept form is y=mx+b, with m as the slope and using point (x,y). So in your case it would be
2=2(3)+b.
2=6+b
2-6=6-6+b
-4=b
So your line intercepts with the y (vertical) axis at -4, or at point (0,-4)
Hope this helps!
2006-06-28 15:13:31 · answer #4 · answered by Crys H. 4 · 0⤊ 0⤋
Given the slope of the line m and one point P1 = (x1,y1) through which the line passes, we can formulate the equation as as:
(y- y1)/(x-x1)= m
We have written this equation in a form which makes it clear that the slope calculated between any point (x,y) on the line and the given point P1 is the same. However, the relationship generally gets simplified algebraically to:
y = m (x-x1)+ y1
Good luck!
2006-06-28 15:21:26 · answer #5 · answered by Kalli 1 · 0⤊ 0⤋
oooh, too many years ago sorry but i cant help.
2006-06-28 15:11:32 · answer #6 · answered by sl62584 3 · 0⤊ 0⤋