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write a slope intercept equation of the line whose graph is parallel to y=4x-9 and has y intercept of (0,2)

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1 Answer

Hi Tiffany,

The equation y = 4x-9 is written in slope-intercept form y= mx+b.  It is called slope-intercept form because when it is written this way you can actually look at the equation and find the slope and the y-intercept without doing any math calculations or manipulations.  So, what I have students do is write the equation then underneath it write y=mx+b and compare the two like so:  

y= mx+b

y= 4x -9

The number underneath the letter m is your slope.  Therefore the slope is m=4.

The number underneath the letter b is your y-intercept. Therefore the y-intercept is b= -9. (***negative 9 because of the minus sign***)

Now lets get the answer.  To do this you have to recognize that the question asks for a line that is "parallel". This is key because parallel lines have the same "slope."  This means you must use the same slope m= 4 again in your new equation.  The other key is that the gave you the y-intercept (0,2).  This is in the form of an x,y coordinate pair.  Well, for the equation you are writing you don't need both numbers.  The first number "0" represents your x-value.  You only need the second number "2" which is the y-value

that you use for your y-intercept "b". So write your equation like so:          

 y= mx+b

underneath write the new equation with number values for m and b:          

y= 4x +2      answer