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Algebra 1 Help Fill In extras?
Okay the points are (-2,-1) and 7,-4 Can someone please find the y and x intercepts and slope intercept form and standard form and point slope form?
Ill vote best answer to first who finds those or most of them.
Thanks.
5 Answers
- NovyLv 51 decade agoFavorite Answer
Best thing to do is first find the slope of the line:
m = (y2 - y1) / (x2 - x1)
m = (-4 + 1) / (7 + 2)
m = -3/9
m = -1/3
Next, we want to do point-slope form:
(y - y1) = m(x - x1)
y + 1 = (-1/3)(x + 2)
Next we want to solve for y to get slope-intercept form:
y + 1 = (-1/3)x - (2/3)
y = (-1/3)x - (5/3)
Now let's find the y-intercept. This is "b" in slope-intercept form so:
y-intercept = (0, -5/3)
Now let's find the x-intercept. This occurs when y=0.
0 = (-1/3)x - (5/3)
(1/3)x = -(5/3)
x = -5
So:
x-intercept = (-5, 0)
Standard form, take your slope-intercept form, and multiply by some clever value so there's no fraction and put in Ax + By = C:
(3)*[y = (-1/3)x - (5/3)]
3y = -1x - 5
x + 3y = -5
- Here2HelpLv 61 decade ago
(x1, y1) = (-2, -1)
(x2, y2) = (7, -4)
Slope, m = (y2 - y1) / (x2 - x1) = (-4 - -1) / (7 - -2) = (-4 + 1) / (7 + 2) = -3/9 = -1/3
y - y1 = m(x - x1)
y - -1 = (-1/3)(x - -2)
y + 1 = (-1/3)(x + 2)
y + 1 = (-1/3)x - 2/3
y = (-1/3)x - 2/3 - 1
y = (-1/3)x - 2/3 - 3/3
y = (-1/3)x - 5/3 <=== Slope-intercept form of the linear equation
Based on this equation, the y-intercept is -5/3; or point (0, -5/3).
(y + 1) = (-1/3)(x + 2) <=== point-slope form of the linear equation
Cross-multiply:
-3(y + 1) = (x + 2)
-3y - 3 = x + 2
x + 3y = -3 - 2
x + 3y = -5 <=== Standard form of the linear equation
To find the x-intercept, find the value of x when y = 0.
x + 3(0) = -5
x + 0 = -5
x = -5 <=== the x-intercept or point (-5, 0)
- Wile E.Lv 71 decade ago
x1 = - 2
y1 = - 1
x2 = 7
y2 = - 4
Slope, m = (y2 - y1) / (x2 - x1)
m = [(- 4) - (- 1)] / (7 - (- 2)]
m = (- 4 + 1) / (7 + 2)
m = - 3 / 9
m = - 1/3
b = y - mx
b = - 1 - [(- 1/3)(- 2)]
b = - 1 - (2/3)
b = - 3/3 - 2/3
b = - 5/3
x-int.: y = 0:
- 1/3 x - 5/3 = 0
- 1/3 x = 5/3
x = (5/3) / (- 1/3)
x = (5/3)(- 3)
x = - 15 / 3
x = - 5
x-int.: (- 5, 0)
¯¯¯¯¯¯¯¯¯¯¯
y-int.: x = 0:
y = - 1/3(0) - 5/3
y = - 5/3
y-int. (0, - 5/3)
¯¯¯¯¯¯¯¯¯¯¯¯
Slope-Intercept Form:
y = - 1/3x - 5/3
¯¯¯¯¯¯¯¯¯¯¯¯¯
Standard Form:
1/3x + y + 5/3 = 0
x + 3y + 5 = 0
¯¯¯¯¯¯¯¯¯¯¯¯¯
Point-Slope Form:
(y - y1) = m(x - x1)
(y - (- 1) = - 1/3[x - (- 2)]
(y + 1) = - 1/3(x + 2)
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
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- 1 decade ago
y = -1/3x - 5/3
y-intercept = -5/3
x-intercept = -5
Slope-intercept form: y=mx+b
the slope, m, is found by finding:
(y2-y1)/(x2-x1) = (-4-(-1))/(7-(-2)) = -1/3
So you have:
y = -1/3x + b, where b is the y-intercept.
To find b, plug in one of your point: (-2,-1)
-1 = (-1/3)(-2) + b, which gives b = -5/3
So you have:
y = -1/3x - 5/3
To find the x-intercept, set y=0
0 = -1/3x -5/3
Solving, you get x = -5