Question 160541
find the value of k so that the line through (4,k) and (-2,-1) is parallel to y=-2x+3/2
:
Parallel lines have the same slope, therefore the slope of the line: m= -2
:
Use the slope formula m = {{{((y2-y1))/((x2-x1))}}}
:
Assign the given coordinate as follows:
x1 = 4; y1 = k
x2 =-2; y2 = -1
m =-2
:
{{{((-1 - k))/((-2 - 4))}}} = -2
:
{{{((-1 - k))/(-6)}}} = -2
:
Multiply both sides by -6, results
-1 - k = -6(-2)
:
-1 - k = +12
:
-k = 12 + 1
:
-k = +13
or 
k = -13
;
Find the equation for this line, so we can check he given coordinates:
y - (-13) = -2(x - 4)
y + 13 = -2x + 8
y = -2x + 8 - 13
y = -2x - 5
If substitute the given values for x, we get the given value for y