Expert: Jenny - 10/24/2004

Question
1.)Write the equation of a line that passes through the point (1, – 4) and is
       perpendicular to y = (–1/4)x + 4; write your answer in standard form;
      enclose fractional coefficients within ( ):
_________________________________________________2.)Solve the system of equations using the elimination (addition) method.
      Show the check of your solution. If there is a unique solution present it
      as an ordered pair in decimal form.
      2.3x + 0.6y = 0.3  and  0.4x – 1.2y = 0.6  

Answer
Hi Jason,

First of all, the slope of the line we are looking for is 4, because to be perpendicular, it needs to have the negative reciprocal slope.

If we use the point-slope formula, we have:

y--4=4(x-1)
y+4=4x-4
In Standard Form, we have Ax+By+C=0

So, we'll add everything to the left side:

-4x+y+8=0

To solve the system of equations:

2.3x+.6y=.3
.4x-1.2y=.6

If we multiply the first equation by 2, we get:

4.6x+1.2y=.6
.4x-1.2y=.6

If we add these two together now, we eliminate the y's from the equation:

5x=1.2

Divide both sides by 5:

x=.24

Now plug that in to solve for y:

.4(.24)-1.2y=.6
.096-1.2y=.6
-1.2y=.504
y=-.42

Good luck!