Please help me!!! Anyone good at Pre Calculus???

Question

If so, pleeease help me on this question...

The section is about slopes of lines.

Find the value of K if the line joining (4,k) and (6,8) and the line joining (-1,4) and (0,8) are (a) parallel, (b) perpendicular.

Answer 1

Line-1 Points are: (4,k) and (6,8)
Line-2 Points are (-1,4) and (0,8)

Slope of line-1 is:
m1=(k-8)/(4-6) = (k-8)/(-2)

Slope of Line-2
m2=(4-8)/(-1-0) = (-4)/(-1) = 4

(a)If lines are parallel, then slopes of line-1 and line- should be equal
That is, m1=m2
Or,(K-8)/(-2) = 4

Solving for K (steps not shown) leads to K = 0

(b)If lines are perpendicular, then (m1)*(m2) = -1
Or, [(K-8)/(-2)] 4 = -1
solve the equation for K
k=8.5 (steps not shown)

Answer 2

First line has slope (k-8)/-2

2nd line has slope 4.

(a) parallel lines have same slope, so (k-8)/-2 = 4

k-8 = -8, k=0

(b) a line perp to a line with slope 4 has slope -1/4

(k-8)/-2= -1/4

4(k-8) = 2

4k-32=2

k=34/4=17/2