Question 399387:  1.  What is the equation of a line that passes through points (-1, 2) and (5, 2)? 
y - 2 = 0 
x - 2 = 0 
y - x - 2 = 0
 
2.  What is the equation of a line with a slope of -2 and a y-intercept of 8? 
x + 2y - 8 = 0 
2x + y - 8 = 0 
2x - y + 8 = 0
 
3.  What is the slope of a line parallel to the line whose equation is y - x = 5? 
-1 
1 
5
 
4.  What is the equation of the line that passes through the point (1, 1) and has a y-intercept of 2. 
x - y + 2 = 0 
x + y - 2 = 0 
x - y - 2 = 0
 
5.  The slope of a line is 1/3 . What is the slope of a line perpendicular to this line? 
-3 
-1/3 
1/3 
3
 
6.  What is the slope of a line perpendicular to the line whose equation is y = 2x + 5? 
slope = -1 
slope = -1/2 
slope = -2
 
7.  What is the equation of a line with a point (-3, 0) and no slope? 
x + 3 = 0 
y + 3 = 0 
x - 3 = 0 
y - 3 = 0
 
8.  What is the equation of a line that passes through point (1, -2) and has a slope of 1/3 . 
3x - y - 7 = 0 
x - 3y + 7 = 0 
x - 3y - 7 = 0
 
9.  What is the equation of the line whose y-intercept is 3 and slope is 1? 
y = x - 3 
y = x + 3 
y = 3x + 1 
 Found 2 solutions by  ewatrrr, MathLover1: Answer by ewatrrr(24785)      (Show Source): 
You can  put this solution on YOUR website!    
Hi 
1. What is the equation of a line that passes through points (-1, 2) and (5, 2) y = 2 
7. What is the equation of a line with a point (-3, 0) and no slope? x = -3 
   
    
2. What is the equation of a line with a slope of -2 and a y-intercept of 8? 
  y = -2x + 8 
3. What is the slope of a line parallel to the line whose equation is y - x = 5? 
 y = x+ 5   parallel lines have equal slopes of m = 1 
4. What is the equation of the line that passes through the point (1, 1) and has a y-intercept of 2.   
y = mx + 2   
1 = m + 2    m = -1 
y = -x + 2 
5. The slope of a line is 1/3 . What is the slope of a line perpendicular to this line?  
⊥ Lines have slopes that are negative reciprocals of one another:  m = - 3/1 
6. What is the slope of a line perpendicular to the line whose equation is y = 2x + 5?  m =  -1/2 
8. What is the equation of a line that passes through point (1, -2) and has a slope of 1/3 .  
y = (1/3)x + b 
-2 = 1/3 + b 
 -7/3 = b 
y = (1/3)x -7/3 
  
 Answer by MathLover1(20850)      (Show Source): 
You can  put this solution on YOUR website! 1.
 
 | Solved by pluggable solver: Finding the Equation of a Line |  
First lets find the slope through the points ( , ) and ( , ) 
   
   
    Start with the slope formula (note: ( , ) is the first point ( , ) and  ( , ) is the second point ( , )) 
   
   
    Plug in  , , ,   (these are the coordinates of given points) 
   
   
    Subtract the terms in the numerator   to get  .  Subtract the terms in the denominator   to get   
   
     
   
   
    Reduce 
   
     
   
  So the slope is 
   
    
   
   
   
   
   
  ------------------------------------------------ 
   
   
Now let's use the point-slope formula to find the equation of the line: 
   
   
   
   
  ------Point-Slope Formula------ 
    where   is the slope, and ( , ) is one of the given points 
   
   
  So lets use the Point-Slope Formula to find the equation of the line 
   
   
    Plug in  ,  , and   (these values are given) 
   
   
   
    Rewrite   as   
   
   
   
    Distribute   
   
   
    Multiply   and   to get  . Now reduce   to get   
   
    Add   to  both sides to isolate y 
   
   
    Combine like terms   and   to get    
   
  ------------------------------------------------------------------------------------------------------------ 
   
  Answer: 
   
   
   
  So the equation of the line which goes through the points ( , ) and ( , )  is:  
   
   
  The equation is now in   form (which is slope-intercept form) where the slope is   and the y-intercept is   
   
   
  Notice if we graph the equation   and plot the points ( , ) and ( , ),  we get this: (note: if you need help with graphing, check out this solver) 
   
   
    Graph of   through the points ( , ) and ( , ) 
   
   
  Notice how the two points lie on the line. This graphically verifies our answer. 
   
   
   |  
  
 
 
answer:   or in slope-intercept form  
 
 
2.
 
 | Solved by pluggable solver: FIND a line by slope and one point |  
 
  What we know about the line whose equation we are trying to find out: 
     
      - it goes through point (0, 8)
  
      - it has a slope of -2
  
    
  
   
  First, let's draw a diagram of the coordinate system with point (0, 8) plotted with a little blue dot: 
   
    
   
    Write this down: the formula for the equation, given point   and intercept a, is 
   
      (see a paragraph below explaining why this formula is correct) 
   
    Given that a=-2, and  , we have the equation of the line: 
   
      
   
    Explanation: Why did we use formula   ? Explanation goes here. We are trying to find equation y=ax+b. The value of slope (a) is already given to us. We need to find b. If a point ( ,  ) lies on the line, it means that it satisfies the equation of the line. So, our equation holds for ( ,  ):   Here, we know a,  , and  , and do not know b. It is easy to find out:  . So, then, the equation of the line is:  .  
   
    Here's the graph: 
   
    
    |  
  
 
 
answer:   or in slope-intercept form  
 
 
3.
 
   or   
 
 
 | Solved by pluggable solver: DESCRIBE a linear EQUATION: slope, intercepts, etc |  
Equation   describes a sloping line. For any  
  equation ax+by+c = 0, slope is  .- X intercept is found by setting y to 0: ax+by=c becomes ax=c. that means that x =  c/a. 5/-1 = -5.
 - Y intercept is found by setting x to 0: the equation becomes by=c, and therefore y = c/b. Y intercept is 5/1 = 5.
 - Slope is --1/1 = 1.
 -  Equation in slope-intercept form: y=1*x+5.
 
  
 |  
  
 
answer: slope is   
 
 
4.
 
 | Solved by pluggable solver: FIND EQUATION of straight line given 2 points |  
hahaWe are trying to find equation of form y=ax+b, where a is slope, and b is intercept, which passes through points (x1, y1) = (1, 1) and (x2, y2) = (0, 2). 
  Slope a is  . 
  Intercept is found from equation  , or  . From that,  
  intercept b is  , or  . 
   
  y=(-1)x + (2) 
   
  Your graph: 
   
    
   |  
  
 
 
answer:  or in slope-intercept form  
 
 
 
5.
 
if slope of the one line is  , the slope of perpendicular line will be  
 
 
so, if  , the slope of perpendicular line will be  
 
 
6.
 
equation   is already in slope-intercept form and you can see that slope is  ; so, the slope of a line perpendicular to this line will be    
 
 
7.
 
 
 | Solved by pluggable solver: FIND a line by slope and one point |  
 
  What we know about the line whose equation we are trying to find out: 
     
      - it goes through point (-3, 0)
  
      - it has a slope of 0
  
    
  
   
  First, let's draw a diagram of the coordinate system with point (-3, 0) plotted with a little blue dot: 
   
    
   
    Write this down: the formula for the equation, given point   and intercept a, is 
   
      (see a paragraph below explaining why this formula is correct) 
   
    Given that a=0, and  , we have the equation of the line: 
   
      
   
    Explanation: Why did we use formula   ? Explanation goes here. We are trying to find equation y=ax+b. The value of slope (a) is already given to us. We need to find b. If a point ( ,  ) lies on the line, it means that it satisfies the equation of the line. So, our equation holds for ( ,  ):   Here, we know a,  , and  , and do not know b. It is easy to find out:  . So, then, the equation of the line is:  .  
   
    Here's the graph: 
   
    
    |  
  
 
 
8.
 
the equation of a line that passes through point (1, -2) and has a slope of 1/3 
 
 
 | Solved by pluggable solver: FIND a line by slope and one point |  
 
  What we know about the line whose equation we are trying to find out: 
     
      - it goes through point (1, -2)
  
      - it has a slope of 0.333333333333333
  
    
  
   
  First, let's draw a diagram of the coordinate system with point (1, -2) plotted with a little blue dot: 
   
    
   
    Write this down: the formula for the equation, given point   and intercept a, is 
   
      (see a paragraph below explaining why this formula is correct) 
   
    Given that a=0.333333333333333, and  , we have the equation of the line: 
   
      
   
    Explanation: Why did we use formula   ? Explanation goes here. We are trying to find equation y=ax+b. The value of slope (a) is already given to us. We need to find b. If a point ( ,  ) lies on the line, it means that it satisfies the equation of the line. So, our equation holds for ( ,  ):   Here, we know a,  , and  , and do not know b. It is easy to find out:  . So, then, the equation of the line is:  .  
   
    Here's the graph: 
   
    
    |  
  
 
you got:
 
 ...or in slope-intercept form  
 
 ...or in slope-intercept form   
 
or 
 
 
 ...or in slope-intercept form   or 
 
so the answer is :  
 
9.
 
 | Solved by pluggable solver: FIND a line by slope and one point |  
 
  What we know about the line whose equation we are trying to find out: 
     
      - it goes through point (0, 3)
  
      - it has a slope of 1
  
    
  
   
  First, let's draw a diagram of the coordinate system with point (0, 3) plotted with a little blue dot: 
   
    
   
    Write this down: the formula for the equation, given point   and intercept a, is 
   
      (see a paragraph below explaining why this formula is correct) 
   
    Given that a=1, and  , we have the equation of the line: 
   
      
   
    Explanation: Why did we use formula   ? Explanation goes here. We are trying to find equation y=ax+b. The value of slope (a) is already given to us. We need to find b. If a point ( ,  ) lies on the line, it means that it satisfies the equation of the line. So, our equation holds for ( ,  ):   Here, we know a,  , and  , and do not know b. It is easy to find out:  . So, then, the equation of the line is:  .  
   
    Here's the graph: 
   
    
    |  
  
 
 
so the answer is :  
 
 
 
 
 
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