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Math Help - Slope and Y-intercept

  1. #1
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    Slope and Y-intercept

    State the slope and y-intercept of each line.

    e) -(x+4)=2(y-3)

    I dont get how that ans is m=-1/2 b=1
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  2. #2
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    Quote Originally Posted by Skoz View Post
    State the slope and y-intercept of each line.

    e) -(x+4)=2(y-3)

    I dont get how that ans is m=-1/2 b=1
    change to slope-intercept form ... y = mx + b
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  3. #3
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    It looks okay, I guess. If you would show your work, I could tell you if you did anything besides looking in the back of the book.
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    I did look in the back of the book I dont understand how the answer could be that.
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  5. #5
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    Quote Originally Posted by Skoz View Post
    State the slope and y-intercept of each line.

    e) -(x+4)=2(y-3)

    I dont get how that ans is m=-1/2 b=1
    this question assumes that you know the definition of "slope" and "y- intercept". Do you?

    The slope of a straight line is \frac{y_1- y_0}{x_1- x_0} where (x_0, y_0) and (x_1, y_1) are any two points on the line. If x= 0, then -(0+4)= 2(y- 3) so -4= 2(y-3). Dividing both sides by 2, -2= y- 3. Adding 3 to both sides, 1= y. (0, 1) is a point on the line. If x= 1, -(1+ 4)= 2(y-3) so -5= 2(y-3) and -\frac{5}{2}= y- 3. y= -\frac{5}{2}+3= \frac{1}{2}. [tex](1, \frac{1}{2})[tex] is also a point on the line. The slope is \frac{1-\frac{1}{2}}{1- 0}= \frac{-1}{2}.

    The "y- intercept" is where the graph crosses ("intercepts") the y-axis which is at x= 0. Putting x= 0 into -(x+ 4)= 2(y- 3) gives -(0+ 4)= -4= 2(y- 3). Dividing both sides by 2, -2= y- 3. Adding 3 to both sides, 1= y. The "y-intercept" is either the value y= 1 or the point (0, 1) depending upon which convention your class is using.
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  6. #6
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    Quote Originally Posted by Skoz View Post
    I did look in the back of the book I dont understand how the answer could be that.
    You are right. I misread another one. I must need another break.

    You still didn't show ANY work.
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